2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
PARTENERIAT TRANSFRONTALIER REPUBLICA MOLDOVA-ROMÂNIAFlorinaTrofin
olaborarea la nivel transfrontalier prin împărtășirea opiniilor, practicilor, metodelor și strategiilor de lucru cu cadrele didactice din Republica Moldova și România pentru îmbunătățirea procesului educațional cu finalități comune.
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
PARTENERIAT TRANSFRONTALIER REPUBLICA MOLDOVA-ROMÂNIAFlorinaTrofin
olaborarea la nivel transfrontalier prin împărtășirea opiniilor, practicilor, metodelor și strategiilor de lucru cu cadrele didactice din Republica Moldova și România pentru îmbunătățirea procesului educațional cu finalități comune.
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...Applitools
During this webinar, Anand Bagmar demonstrates how AI tools such as ChatGPT can be applied to various stages of the software development life cycle (SDLC) using an eCommerce application case study. Find the on-demand recording and more info at https://applitools.info/b59
Key takeaways:
• Learn how to use ChatGPT to add AI power to your testing and test automation
• Understand the limitations of the technology and where human expertise is crucial
• Gain insight into different AI-based tools
• Adopt AI-based tools to stay relevant and optimize work for developers and testers
* ChatGPT and OpenAI belong to OpenAI, L.L.C.
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...
Curs 6 Data Mining
1. Introducere ˆ Data Mining
ın
Analiza asocierilor: concepte de baz˘
a
Lucian Sasu, Ph.D.
Universitatea Transilvania din Bra¸ov, Facultatea de Matematic˘ ¸i Informatic˘
s as a
April 5, 2012
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 1 / 73
2. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 2 / 73
3. Notiuni
¸
ˆ cadrul vˆnz˘rilor din magazine se ˆ
In a a ınregistreaz˘ continutul co¸urilor
a ¸ s
de cump˘r˘turi achizitionate = tranzactii
aa ¸ ¸
Problem˘: pentru un set de tranzactii s˘ se determine regulile care
a ¸ a
dau predispozitia aparitiei unui obiect pe baza existentei altor obiecte
¸ ¸ ¸
ˆ
ıntr-un co¸s
Exemplu de tranzactii:
¸
TID Obiecte
1 {pˆine, lapte}
a
2 {pˆine, scutece, bere, ou˘}
a a
3 {lapte, scutece, bere, suc}
4 {pˆine, lapte, scutece, bere}
a
5 {pˆine, lapte, scutece, suc}
a
Table: Tranzactii de tip co¸ de cump˘r˘turi
¸ s aa
TID = Transaction ID
Exemplu de regul˘ ce se poate extrage: {scutece} −→ {bere}
a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 3 / 73
4. Notiuni
¸
Regula sugereaz˘ c˘ ar exista o relatie de dependent˘ ˆ
a a ¸ ¸a ıntre vˆnzarea
a
de scutece ¸i cea de bere
s
Remarc˘: regula dat˘ este directional˘; nu ˆ
a a ¸ a ınseamn˘ neap˘rat ¸i c˘
a a s a
{bere} −→ {scutece}
Moduri de exploatare a unor astfel de reguli:
se scade pretul obiectelor din antecedentul regulii, se cre¸te pretul celor
¸ s ¸
din consecvent
se face cross-selling
se decide dispunerea pe raft a produselor
se face reclam˘ sau ofert˘ personalizat˘, gruparea produselor ˆ
a a a ın
cataloage de prezentare
Alte medii de aplicare: bioinformatic˘, diagnostic medical, web
a
mining, analiza ¸tiintific˘ a datelor
s ¸ a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 4 / 73
5. Notiuni
¸
Probleme:
descoperirea de pattern–uri ˆ seturi mari de date este o problem˘
ın a
intensiv˘ computational
a ¸
o parte din relatiile descoperite pot fi pur ¸i simplu rodul ˆ ampl˘rii
¸ s ıntˆ a
evaluarea regulilor obtinute este un pas absolut necesar
¸
semnul de implicatie ˆ acest context ˆ
¸ ın ınseamn˘ aparitie concomitent˘,
a ¸ a
nu cauzalitate
de citit: Correlation does not imply causation (Wikipedia)
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 5 / 73
6. Notiuni, definitii
¸ ¸
Posibil mod de reprezentare a tranzactiilor:
¸
TID Pˆine
a Lapte Scutece Bere Ou˘a suc
1 1 1 0 0 0 0
2 1 0 1 1 1 0
3 0 1 1 1 0 1
4 1 1 1 1 0 0
5 1 1 1 0 0 1
Table: Reprezentare binar˘ a datelor tranzactiei
a ¸
Reprezentarea binar˘ este asimetric˘: prezenta unui produs este mai
a a ¸
important˘ decˆt lipsa lui
a a
Reprezentare voit simplist˘, omitˆnd cantitatea de achizitie
a ¸a ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 6 / 73
7. Notiuni, definitii
¸ ¸
Multime de produse (simplu: multime; eng: itemset) — colectie de
¸ ¸ ¸
unul sau mai multe obiecte
k–multime (eng: k-itemset) — o multime compus˘ din k obiecte
¸ ¸ a
(produse)
Num˘rul de suport al unei multimi σ(·) (eng: support count) —
a ¸
frecventa de aparitie a acelei multimi
¸ ¸ ¸
σ(X ) = |{ti : X ⊆ ti , ti ∈ T }| unde T este multimea tuturor
¸
tranzactiilor, |U| este num˘rul de elemente (cardinalul) al multimii U
¸ a ¸
Exemplu: σ({lapte, paine, scutece}) = 2
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 7 / 73
8. Notiuni, definitii
¸ ¸
Regul˘ de asociere (regul˘): o expresie de forma X −→ Y unde X , Y
a a
sunt multimi de produse, X ∩ Y = ∅
¸
Definitie (Suportul unei reguli)
¸
Suportul regulii X −→ Y pentru o multime de N tranzactii este fractia de
¸ ¸ ¸
tranzactii care contin produsele din X ∪ Y :
¸ ¸
σ(X ∪ Y )
s(X −→ Y ) = (1)
N
Definitie (Confidenta unei reguli)
¸ ¸
Confidenta regulii X −→ Y este num˘rul de tranzactii care contin pe X ¸i
¸ a ¸ ¸ s
Y raportat la cele care contin doar pe X :
¸
σ(X ∪ Y )
c(X −→ Y ) = (2)
σ(X )
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 8 / 73
9. Notiuni, definitii
¸ ¸
Exemplu: pentru datele din tabelul de mai jos
TID Obiecte
1 {pˆine, lapte}
a
2 {pˆine, scutece, bere, ou˘}
a a
3 {lapte, scutece, bere, suc}
4 {pˆine, lapte, scutece, bere}
a
5 {pˆine, lapte, scutece, suc}
a
Consider˘m regula {lapte, scutece} −→ {bere}
a
Num˘rul de suport pentru {lapte, scutece, bere} este 2; num˘rul total
a a
de tranzactii este 5, deci suportul este 2/5
¸
Confidenta: sunt 3 tranzactii care contin {lapte, scutece}, deci
¸ ¸ ¸
confidenta este 2/3
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 9 / 73
10. Notiuni, definitii
¸ ¸
De ce se folose¸te suportul?
s
o regul˘ cu suport mic poate ˆ
a ınsemna o leg˘tur˘ ˆ ampl˘toare
a a ıntˆ a
o regul˘ cu suport mic s–ar putea s˘ fie neprofitabil˘
a a a
suportul poate elimina regulile neinteresante
De ce se folose¸te confidenta?
s ¸
m˘soar˘ ˆ
a a ıncrederea ˆ rezultatul aplic˘rii unei reguli
ın a
pentru regula X −→ Y o confident˘ mare arat˘ ˆ ce m˘sur˘ aparitia
¸a a ın a a ¸
multimii X va duce la aparitia multimii Y
¸ ¸ ¸
c(X −→ Y ) poate fi interpretat˘ ca probabilitatea conditionat˘
a ¸ a
P(Y |X )
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 10 / 73
11. Notiuni, definitii
¸ ¸
Definitie (Descoperirea relatiilor de asociere)
¸ ¸
Dˆndu–se o multime de tranzactii T , s˘ se g˘seasc˘ toate regulile cu
a ¸ ¸ a a a
suport ≥ minsup ¸i confident˘ conf ≥ minconf , unde minsup ¸i minconf
s ¸a s
sunt praguri date.
Abordare brute-force:
se genereaz˘ toate regulile de asociere posibile
a
se calculeaz˘ suportul ¸i confidenta fiec˘rei reguli
a s ¸ a
se elimin˘ regulile care nu respect˘ pragurile minconf ¸i minsup date
a a s
Complexitate de calcul prohibitiv˘: num˘rul de reguli pentru d
a a
produse este:
R = 3d − 2d+1 + 1
(tem˘ pentru acas˘)
a a
Pentru cele 6 produse din tranzactiile date am avea 602 reguli; pentru
¸
minsup = 20% ¸i minconf = 50%, mai mult de 80% din regulile
s
generate sunt eliminate!
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 11 / 73
12. Pa¸i de lucru
s
Observatie important˘: suportul regulii X −→ Y depinde doar de
¸ a
num˘rul suport al multimii X ∪ Y
a ¸
Pentru multimea {bere, scutece, lapte} se pot genera 6 reguli:
¸
{bere, scutece} −→ {lapte}, {bere} −→ {scutece, lapte} etc.; toate
acestea au acela¸i suport, indiferent de partitionarea ˆ
s ¸ ın
antecedent/consecvent
Dac˘ o multime nu este frecvent˘, atunci toate regulile ce se pot
a ¸ a
construi pe baza ei pot fi eliminate f˘r˘ a le mai calcula confidenta
aa ¸
Concluzie: se poate decupla calculul suportului ¸i al confidentei
s ¸
Pa¸ii de lucru:
s
1 generarea multimilor frecvente, i.e. al celor pentru care suportul este
¸
cel putin minsup
¸
2 generarea regulilor pe baza multimilor frecvente
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 12 / 73
13. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 13 / 73
14. Problema gener˘rii multimilor frecvente
a ¸
Generarea multimilor frecvente este solicitant˘ computational: pentru o
¸ a ¸
multime de k produse se pot realiza 2
¸ k − 1 potentiale multimi frecvente
¸ ¸
(se exclude ∅)
Figure: Latice de multimi
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 14 / 73
15. Varianta brute-force:
Fiecare multime candidat din latice este considerat ca un candidat de
¸
multime frecvent˘
¸ a
Se calculeaz˘ num˘rul suport al fiec˘rui candidat prin scanarea bazei
a a a
de date
Dac˘ un candidat e inclus ˆ
a ıntr–o tranzactie se incrementeaz˘ num˘rul
¸ a a
suport
Figure: Diferiti parametri ai datelor de intrare
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 15 / 73
16. Complexitate si remedii
Complexitate: O(NMw ) unde: N = num˘rul de tranzactii,
a ¸
M = 2k − 1 este num˘rul de multimi candidat, w este num˘rul
a ¸ a
maxim de obiecte dintr-o tranzactie
¸
Modalit˘¸i de reducere a complexit˘¸ii:
at at
reducerea num˘rului de multimi candidat M – de exemplu prin
a ¸
principiul Apriori
reducerea num˘rului de comparatii la confruntarea unei multimi cu o
a ¸ ¸
tranzactie prin structuri de date eficiente
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 16 / 73
17. Principiul Apriori
Teorem˘ (Principiul Apriori)
a
Dac˘ un set este frecvent, atunci oricare din subseturile sale este de
a
asemenea frecvent.
Demonstratie: Pentru o tranzactie care contine multimea de obiecte
¸ ¸ ¸ ¸
X = {c, d, e} este evident c˘ ea contine ¸i oricare din submultimile lui X :
a ¸ s ¸
{c, d}, {c, e} etc. Mai mult, pentru o submultime a lui X poate exista o
¸
tranzactie care s˘ o contin˘, dar s˘ nu contin˘ ¸i pe X . Astfel, num˘rul
¸ a ¸ a a ¸ as a
suport pentru o submultime a lui X este cel putin num˘rul suport al lui X .
¸ ¸ a
teorema afirm˘ c˘:
a a
∀X , Y : (X ⊆ Y ) ⇒ s(X ) ≥ s(Y )
adic˘ o proprietate de anti-monotonie a suportului
a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 17 / 73
18. Eliminarea multimilor infrecvente
¸
Contrapozitia teoremei este util˘ pentru a face eliminarea multimilor
¸ a ¸
care nu pot fi frecvente: Dac˘ un set nu este frecvent, atunci oricare
a
superset al lui nu poate s˘ fie frecvent.
a
Figure: Retezarea multimilor infrecvente
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 18 / 73
19. Strategie
Se porne¸te cu 1-multimi formate din cˆte un obiect
s ¸ a
1-multimile nefrecvente se elimin˘
¸ a
Se genereaz˘ 2-multimi combinˆnd 1-multimi frecvente
a ¸ a ¸
Pentru 2-multimile generate se calculeaz˘ suportul; cele nefrecvente
¸ a
se elimin˘
a
Se continu˘ procedeul pentru 3-multimi etc.
a ¸
Pe baza principiului Apriori, pentru generarea k-multimilor frecvente
¸
candidat se iau ˆ considerare doar (k − 1)-multimile frecvente
ın ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 19 / 73
20. Exemplu de aplicare
Figure: Generarea multimilor frecvente folosind principiul Apriori
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 20 / 73
21. Schita algoritmului Apriori
¸
k =1
Se genereaz˘ 1-multimi frecvente
a ¸
Repet˘ pˆn˘ cˆnd nu se mai pot identifica multimi frecvente:
a a a a ¸
se genereaz˘ (k + 1)-multimi candidat folosind k-multimile frecvente
a ¸ ¸
de la pasul anterior
se ¸terg (k + 1)-multimile candidat care contin k-multimi infrecvente
s ¸ ¸ ¸
(cu suportul sub prag)
se contorizeaz˘ suportul fiec˘rei (k + 1)−multimi prin parcurgerea
a a ¸
tranzactiilor
¸
se ¸terg (k + 1)-multimile candidat care nu sunt frecvente
s ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 21 / 73
23. Probleme ce trebuie rezolvate eficient pentru Apriori
Generarea multimilor candidat ¸i retezarea
¸ s
1 generarea de k-multimi folosind (k − 1)-multimi frecvente
¸ ¸
2 eliminarea candidatilor care nu au suportul peste pragul impus
¸
Calculul num˘rului suportul al unei multimi
a ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 23 / 73
24. Generarea multimilor candidat (var 1)
¸
Generarea multimilor candidat:
¸
orice algoritm trebuie s˘ evite generarea de prea multe multimi candidat
a ¸
trebuie s˘ asigure generarea unei familii complete de multimi candidat
a ¸
trebuie s˘ evite generarea aceleia¸i multimi candidat de mai multe ori
a s ¸
({a, b, c} poate proveni din {a, b} ∪ {c} sau din {a} ∪ {b, c} etc.)
Sunt mai multi algoritmi ˆ aceast˘ directie
¸ ın a ¸
Metoda fortei brute:
¸
Se consider˘ fiecare posibilitate de a obtine o k-multime
a ¸ ¸
Se elimin˘ candidatii cu suport prea mic
a ¸
Generarea e simpl˘, calculul suportului pentru fiecare candidat este
a
costisitor
Complexitatea metodei: O(d · 2d−1 )
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 24 / 73
25. Generarea multimilor candidat (var 2)
¸
Metoda Fk−1 × F1 :
se pleac˘ de la fiecare (k − 1)-multime frecvent˘ ¸i se extinde cu
a ¸ as
obiecte (1-multimi) frecvente
¸
procedeul e complet
se poate ajunge la generarea multipl˘ a aceleia¸i k-multimi
a s ¸
evitare: fiecare multime este mentinut˘ sortat˘ lexicografic: {a, b, c} ¸i
¸ ¸ a a s
nu {b, a, c} sau altfel
extinderea unei multimi Fk−1 = {ob1 , ob2 , . . . , obk−1 } se face numai cu
¸
multimi F1 = {x} unde obk−1 < x
¸
complexitate: O( k k|Fk−1 ||F1 |)
ˆ a se pot genera prea multe k-multimi candidat
ınc˘ ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 25 / 73
26. Generarea multimilor candidat (var 3)
¸
Metoda Fk−1 × Fk−1 :
se reunesc dou˘ (k − 1)-multimi doar dac˘ primele k − 2 elemente din
a ¸ a
ele sunt identice (se presupune ordinea lexicografic˘): a
mai clar: dac˘ A = {a1 , a2 , . . . ak−1 } ¸i B = {b1 , b2 , . . . bk−1 } sunt
a s
dou˘ (k − 1)-multimi, atunci ele se reunesc doar dac˘:
a ¸ a
ai = bi , ∀i = 1, . . . , k − 2, ak−1 = bk−1
este varianta propus˘ ˆ articolul ce introduce algoritmul Apriori
a ın
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 26 / 73
27. Reducerea num˘rului de comparatii
a ¸
Varianta brute force: se scaneaz˘ toat˘ baza de date pentru a
a a
determina valoarea suport a fiec˘rei multimi candidat
a ¸
Posibil, dar neeficient
Pentru a reduce num˘rul de comparatii stoc˘m candidatii ˆ
a ¸ a ¸ ıntr–un
arbore de dispersie (hash tree)
Rezultat: ˆ loc de a compara fiecare tranzactie cu fiecare multime
ın ¸ ¸
candidat, se compar˘ fiecare tranzactie cu grupuri de candidati din
a ¸ ¸
arbore; se vor actualiza doar valorile suport pentru multimi candidat
¸
din grupurile g˘site
a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 27 / 73
28. Crearea arborelui de dispersie, exemplu
Consider˘m functia de dispersie h(p) = p mod 3
a ¸
Impunem restrictia ca ˆ
¸ ıntr–un nod frunz˘ s˘ nu avem mai mult de 3
a a
multimi reprezentate; dac˘ este cazul, un nod va fi fragmentat ˆ
¸ a ın
noduri copil
Presupunem c˘ avem multimile candidat: {1, 4, 5}, {1, 2, 4}, {4, 5, 7},
a ¸
{1, 2, 5}, {4, 5, 8}, {1, 5, 9}, {1, 3, 6}, {2, 3, 4}, {5, 6, 7}, {3, 4, 5},
{3, 5, 6}, {3, 5, 7}, {6, 8, 9}, {3, 6, 7}, {3, 6, 8},
Reprezentarea ˆ arbore de dispersie:
ın
Figure: Arbore de dispersie pentru familia de multimi candidat
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 28 / 73
33. C˘utarea potrivirilor ˆ
a ıntre tranzactii ¸i multimi candidat
¸ s ¸
Figure: Se ia in considerare primul obiect al unei posibile 3-multimi ce se
regaseste in tranzactie
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 33 / 73
34. C˘utarea potrivirilor ˆ
a ıntre tranzactii ¸i multimi candidat
¸ s ¸
Figure: Se ia in considerare al doilea obiect al unei posibile 3-multimi ce se
regaseste in tranzactie
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 34 / 73
35. C˘utarea potrivirilor ˆ
a ıntre tranzactii ¸i multimi candidat
¸ s ¸
Figure: Se ia in considerare al treilea obiect al unei posibile 3-multimi ce se
regaseste in tranzactie
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 35 / 73
36. Complexitatea computational˘ a gener˘rii de multimi
¸ a a ¸
frecvente
Factorii care influenteaz˘ complexitatea gener˘rii:
¸ a a
Alegerea valorii de minsup
mic¸orarea lui minsup duce la mai multe multimi declarate ca frecvente
s ¸
Num˘rul de obiecte din setul de date
a
poate duce la m˘rirea cardinalului maxim de multime frecvent˘
a ¸ a
dac˘ num˘rul de multimi frecvente cre¸te ¸i el atunci atˆt efortul
a a ¸ s s a
computational cˆt ¸i costul I/O cre¸te
¸ a s s
Dimensiunea bazei de date
fiecare tranzactie se compar˘ cu multimile candidat; num˘r mare de
¸ a ¸ a
tranzactii ⇒ timp crescut pentru eliminarea multimilor candidat
¸ ¸
nefrecvente
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 36 / 73
37. Complexitatea computational˘ a gener˘rii de multimi
¸ a a ¸
frecvente
Generarea 1-multimilor frecvente: O(Nw )
¸
Generarea multimilor candidat:
¸
w w
(k−2)|Ck | < costul unific. a 2 k − 1-multimi <
¸ (k−2)|Fk−1 |2
k=2 k=2
Eliminarea de multimi candidat infrecvente:
¸
w
O k(k − 2)|Ck |
k=2
Calcularea suportului
k
O N Cw αk
k
unde αk este costul actualiz˘rii unei k-multimi din arborele de
a ¸
dispersie.
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 37 / 73
38. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 38 / 73
39. Generarea regulilor
Enunt: dˆndu–se o multime frecvent˘ L, s˘ se g˘seasc˘ toate
¸ a ¸ a a a a
submultimile nevide f ⊂ L astfel ˆ at regula f −→ L − f s˘ aib˘
¸ ıncˆ a a
confidenta minim˘ cerut˘
¸ a a
Pentru multimea frecvent˘ {A, B, C , D} regulile candidat ce se pot
¸ a
obtine sunt: ABC −→ D, ABD −→ C , ACD −→ B,
¸
BCD −→ A, A −→ BCD, B −→ ACD, C −→ ABD,
D −→ ABCAB −→ CD, AC −→ BD, AD −→ BC ,
BC −→ AD, BD −→ AC , CD −→ AB
Pentru k = |L| sunt 2k − 2 reguli care se pot genera (ignor˘m regulile
a
cu antecedent sau consecvent nul)
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 39 / 73
40. Generarea regulilor
Nu avem nicio proprietate de tip (anti)monotonie pentru confidenta
¸
regulilor
s ˜ ˜
Pentru o regul˘ X −→ Y ¸i X ⊂ X , Y ⊂ Y nu avem nicio relatie
a ¸
˜ ˜
a ıntre c(X −→ Y ) ¸i c(X −→ Y )
permanent valabil˘ ˆ s
Dar avem o teorem˘ ⌣
a ¨
Teorem˘
a
Dac˘ o regul˘ X −→ Y − X nu satisface conditia de confident˘ minim˘
a a ¸ ¸a a
c(X −→ Y − X ) ≥ minconf atunci nicio regul˘ X ′ −→ Y − X ′ cu X ′ ⊂ X
a
nu va avea nici ea confidenta minim˘.
¸ a
Demonstratie: pentru regulile X ′ −→ Y − X ′ ¸i X −→ Y − X confidentele
¸ s ¸
sunt s1 = σ(Y )/σ(X ′ ) respectiv s = σ(Y )/σ(X ). Pentru X ′ ⊂ X avem
2
c˘ σ(X ′ ) ≥ σ(X ). Ca atare, s1 ≤ s2 ¸i deci prima regul˘ nu poate avea o
a s a
confident˘ mai mare decˆt a doua.
¸a a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 40 / 73
41. Generarea regulilor: strategie de retezare
Figure: Retezarea regulilor aplicand teorema 2
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 41 / 73
42. Retezarea regulilor ˆ algoritmul Apriori
ın
Se genereaz˘ toate regulile care au doar un element ˆ antecedent
a ın
Se combin˘ reguli care au ceva comun ˆ sufix: de exemplu, din
a ın
{a, c, d} −→ {b} ¸i {a, b, d} −→ {c} se genereaz˘ {a, d} −→ {b, c}
s a
Se fac elimin˘rile de reguli conform teoremei 2
a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 42 / 73
43. Generarea regulilor ˆ algoritmul Apriori
ın
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 43 / 73
44. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 44 / 73
45. Reprezentarea compact˘ a multimilor frecvente
a ¸
Num˘rul de multimi frecvente poate s˘ fie prohibitiv
a ¸ a
Se poate identifica o familie reprezentativ˘ de multimi frecvente din
a ¸
care se pot obtine toate celelalte multimi frecvente
¸ ¸
Variante: multimi frecvente maximale ¸i multimi frecvente ˆ
¸ s ¸ ınchise
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 45 / 73
46. Multimi frecvente maximale
¸
Definitie
¸
O multime frecvent˘ maximal˘ este o multime frecvent˘ pentru care toate
¸ a a ¸ a
superseturile imediate sunt infrecvente.
(superset imediat al lui X este multime X ∪ {y }, y ∈ X )
¸
Figure: Familia de multimi frecvente maximale este reprezentat˘ cu verde
¸ a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 46 / 73
47. Utilitatea multimilor frecvente maximale
¸
Toate multimile frecvente sunt generate de multimile frecvente
¸ ¸
maximale
Ex: multimile frecvente din figura anterioar˘ sunt ˆ
¸ a ıntr-una din
situatiile:
¸
1 multimi care ˆ
¸ ıncep cu litera a ¸i contin c, d sau e
s ¸
2 multimi care ˆ
¸ ıncep cu b, c, d sau e.
Exist˘ algoritmi care pot exploata eficient multimile frecvente
a ¸
maximale, f˘r˘ a genera toate submultimile
aa ¸
Problem˘: multimile frecvente maximale nu dau o modalitate de
a ¸
calcul al suportului submultimilor frecvente pe care le genereaz˘
¸ a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 47 / 73
48. Multimi frecvente ˆ
¸ ınchise
Definitie (Multimi ˆ
¸ ¸ ınchise)
O multime X este ˆ
¸ ınchis˘ dac˘ niciunul din superseturile imediate ale sale
a a
nu are acela¸i suport ca ea.
s
Definitie (Multimi frecvente ˆ
¸ ¸ ınchise)
O multime X este frecvent˘ ˆ
¸ a ınchis˘ dac˘ este ˆ
a a ınchis˘ ¸i frecvent˘.
as a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 48 / 73
49. Multimi frecvente maximale vs. frecvente ˆ
¸ ınchise
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 49 / 73
50. Utilitatea multimilor frecvente ˆ
¸ ınchise
Set de tranzactii:
¸
3 grupuri: {A1, . . . , A5}, {B1, . . . , B5}, {C 1, . . . , C 5}
Pentru minsup = 20% avem num˘r total de multimi frecvente = 93
a ¸
Dar exist˘ doar 3 multimi frecvente ˆ
a ¸ ınchise: {A1, . . . , A5},
{B1, . . . , B5}, {C 1, . . . , C 5}
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 50 / 73
51. Relatia ˆ
¸ ıntre diferite tipuri de multimi
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 51 / 73
52. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 52 / 73
53. Metode alternative pentru generarea de multimi frecvente
¸
Apriori este unul din primii algoritmi eficienti care evit˘ explozia
¸ a
combinatorial˘ a gener˘rii seturilor frecvente
a a
Principiul de baz˘: retezarea conform teoremei de la pagina 40
a
Deficient˘: num˘rul mare de operatii de I/O
¸a a ¸
Deficient˘: pentru seturile de tranzactii dense performanta scade mult
¸a ¸ ¸
Metode alternative: “de la general la specific”, “de la specific la
general”, c˘utare bidirectional˘
a ¸ a
Ideea de baz˘: determinarea multimilor frecvente este o problem˘ de
a ¸ a
c˘utare ˆ graful laticii multimilor
a ın ¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 53 / 73
54. Metode alternative pentru generarea de multimi frecvente
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 54 / 73
55. Metode alternative pentru generarea de multimi frecvente
¸
“De la general la specific”: ˆ stilul algoritmului Apriori, de la o
ın
(k − 1)-multime se ajunge la o k-multime; strategia e bun˘ dac˘
¸ ¸ a a
lungimea maxim˘ a unei multimi frecvente nu este prea mare
a ¸
“De la specific la general”: se poate adapta principiul Apriori
C˘utare bidirectional˘: combinatie a precedentelor dou˘, necesit˘ mai
a ¸ a ¸ a a
mult˘ memorie, dar permite determinarea rapid˘ a zonei de delimitare
a a
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 55 / 73
56. Metode alternative pentru generarea de multimi frecvente
¸
Clase de echivalent˘: se partitioneaz˘ multimea nodurilor din latice ˆ
¸a ¸ a ¸ ın
clase de echivalent˘; se trece la o alt˘ partitie numai cˆnd s–a
¸a a ¸ a
terminat de explorat partitia curent˘
¸ a
Exemple de partitionare: arbori de tip prefix/sufix
¸
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 56 / 73
57. Metode alternative pentru generarea de multimi frecvente
¸
C˘utarea “mai ˆ ai ˆ l˘¸ime”: algoritmul Apriori functioneaz˘ astfel,
a ıntˆ ın at ¸ a
trecˆnd la k-multimi numai dup˘ ce s–au epuizat toate
a ¸ a
(k − 1)-multimile
¸
C˘utarea ˆ adˆncime este o variant˘ folosit˘ pentru a determina
a ın a a a
multimile frecvente maximale
¸
Odat˘ g˘sit˘ o multime maximal˘, se poate face retezare
a a a ¸ a
Figure: Parcugeri alternative
lucian.sasu@ieee.org (UNITBV) Curs 6 April 5, 2012 57 / 73
58. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
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59. Problema evalu˘rii asocierilor
a
Algoritmii pot duce la producerea unui num˘r mare de reguli
a
Multe pot fi neinteresante sau redundante
Exemplu de redundant˘: dac˘ regulile {A, B, C } −→ {D} ¸i
¸a a s
{A, B} −→ {D} au acela¸i suport ¸i confident˘
s s ¸a
Se pot folosi functii de m˘surare a gradului de interes care s˘ reduc˘
¸ a a a
/sorteze regulile
ˆ cele prezentate pˆn˘ acum, doar suportul ¸i confidenta erau
In a a s ¸
considerate
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60. Schema unui proces de extragere de cuno¸tinte
s ¸
Figure: Pa¸ii unui proces de extragere de cuno¸tinte. Postprocesarea contine
s s ¸ ¸
evaluarea regulilor
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61. Moduri de cuantificare al gradului de interes
Functii obiective:
¸
folosesc statistici derivate din date pentru a determina gradul de interes
suport, confident˘, corelatie
¸a ¸
Functii subiective:
¸
se refer˘ la grad de interes pentru cunoa¸terea uman˘
a s a
exemplu: {unt} −→ {paine} este de a¸teptat ¸i deci neinteresant; dar
s s
{scutece} −→ {bere} este ceva surprinz˘tora
modalit˘¸i de ˆ
at ıncorporare a subiectivismului:
vizualizare
filtrare bazat˘ pe ¸abloane
a s
ierarhie de concepte
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62. M˘sura obiectiv˘ a interesului
a a
M˘sur˘ obiectiv˘: modalitate dependent˘ de date
a a a a
Necesit˘ interventie minim˘ din partea utilizatorului
a ¸ a
Punct de plecare pentru diferite m˘suri, pe perechi de variabile binare:
a
tabel de contingent˘
¸a
Y Y Total
X f11 f10 f1+
X f01 f00 f0+
Total f+1 f+0 N
Table: Tabel de contingent˘ pentru regula X −→ Y . O valoare de forma (·)
¸a
reprezint˘ lipsa obiectului asociat ˆ tranzatie. f1+ (f+1 ) reprezint˘ valoarea
a ın ¸ a
suport pentru X (respectiv Y ).
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63. Limit˘ri ale cuplului suport-confident˘
a ¸a
Consider˘m studiul leg˘turii ˆ
a a ıntre cei care beau ceai sau cafea:
Cafea Cafea Total
Ceai 150 50 200
Ceai 650 150 800
Total 800 200 1000
Table: Preferinte de consum.
¸
Consider˘m regula: {Ceai} −→ {Cafea}: suport 15%, confident˘
a ¸a
75%
Remarc˘m ˆ a c˘ procentul celor care beau cafea este de 80%, mai
a ıns˘ a
mult decˆt confidenta anterioar˘
a ¸ a
Deci regula {Ceai} −→ {Cafea} d˘ o indicatie gre¸it˘ fat˘ de starea
a ¸ s a ¸a
actual˘ a datelor; ¸tiind c˘ o persoan˘ bea ceai, asta va sc˘dea ¸ansa
a s a a a s
ei ca s˘ bea cafea
a
Cauza: m˘sura de confident˘ ignor˘ suportul multimii consecvent
a ¸a a ¸
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64. Alte functii obiective de m˘surare a gradului de interes
¸ a
factor de ridicare (eng: lift)
c(A −→ B)
lift(A −→ B) =
s(B)
interes:
s(A, B) =1 pentru A ¸i B independente
s
I (A, B) = : >1 pentru A ¸i B pozitiv corelate
s
s(A) · s(B)
<1 pentru A ¸i B negativ corelate
s
corelatia Pearson pentru variabile binare:
¸
f11 f00 − f01 f10
φ= ∈ [−1, 1]
f1+ f+1 f0+ f+0
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65. Alte functii obiective de m˘surare a gradului de interes
¸ a
Figure: M˘suri propuse
a
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66. Sortarea pe baza diferitelor functii
¸
Pe baza functiilor se pot face ordon˘ri ale regulilor
¸ a
Ordinea poate s˘ difere de la o functie de interes la alta
a ¸
Figure: 10 exemple de tabele de contingent˘
¸a
Figure: Sortarea pe baza diferitelor reguli
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67. Propriet˘¸i ale functiilor obiective
at ¸
De v˘zut din bibliografie:
a
Proprietatea de inversiune
Proprietatea de ad˘ugare nul˘
a a
Proprietatea de scalare
De citit: paradoxul lui Simpson ¸i necesitatea stratific˘rii datelor ˆ
s a ınaintea
extragerii de reguli
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68. Outline
1 Notiuni, definirea problemei
¸
2 Generarea multimilor frecvente
¸
3 Generarea regulilor
4 Reprezentarea compact˘ a multimilor frecvente
a ¸
5 Metode alternative pentru generarea de multimi frecvente
¸
6 Evaluarea regulilor de asociere
7 Efectul distributiei oblice
¸
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69. Distributii oblice
¸
Uneori datele au urm˘toarea form˘: foarte multe obiecte cu suport
a a
mic, putine cu suport mare
¸
O atare distributie este puternic neechilibrat˘ (eng: skewed) ¸i nu
¸ a s
poate fi tratat˘ uniform
a
Dac˘ pragul minsup este ales prea mic atunci algoritmul Apriori (sau
a
oricare altul) poate genera excesiv de multe multimi frecvente ⇒
¸
consum mare de memorie, posibil relatii ˆ ampl˘toare
¸ ıntˆ a
Dac˘ minsup este prea mare se pot rata ni¸te reguli utile
a s
exemplu: bijuterii - se cump˘r˘ rar ˆ comparatie cu alte produse, dar
aa ın ¸
profitul adus e considerabil
Pentru setul de date Public Use Microarray Sample census data
distributia datelor este:
¸
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70. Distributii oblice
¸
Figure: Distributie oblic˘ pentru setul de date textcolorbluePUMS census data
¸ a
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71. Distributii oblice
¸
Dac˘ se las˘ valoare minsup mic˘, atunci o multime poate s˘ combine
a a a ¸ a
obiecte cu suport mare ¸i mic
s
Obiectele din multime ˆ a pot avea o corelatie mic˘
¸ ıns˘ ¸ a
Atfel de multimi se numesc ¸abloane cu suport ˆ
¸ s ıncruci¸at (eng:
s
cross-support patterns)
Pentru minsup = 0.05% avem 18847 perechi frecvente, din care 93%
sunt cu obiecte din G1 ¸i G3; corelatia maxim˘ este ˆ a 0.029 - prea
s ¸ a ıns˘
putin
¸
Chiar m˘rirea pragului minconf poate fi inefectiv˘; consecventul unei
a a
reguli poate avea suport mare deci ¸abloane cu suport ˆ
s ıncluci¸at pot
s
ˆ a s˘ apar˘
ınc˘ a a
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72. Distributii oblice
¸
Definitie (Sabloane cu suport ˆ
¸ ¸ ıncruci¸at)
s
Un ¸ablon cu suport ˆ
s ıncruci¸at este o multime X = {i1 , i2 , . . . , ik } pentru
s ¸
care raportul suporturilor
min[s(i1 ), s(i2 ), . . . , s(ik )]
r (X ) = (3)
max[s(i1 ), s(i2 ), . . . , s(ik )]
este mai mic decˆt un prag specificat de utilizator hc .
a
Un alt mod de detectare a ¸abloanelor cu suport ˆ
s ıncruci¸at: se
s
examineaz˘ confidenta minim˘ care se poate extrage dintr–o multime
a ¸ a ¸
dat˘, i.e. m˘sura h-confident˘:
a a ¸a
s (i1 , i2 , . . . , ik )
max [s(i1 ), s(i2 ), . . . , s(ik )]
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73. Distributii oblice
¸
Criteriul de eliminare a unui ¸ablon ˆ
s ıncruci¸at X : ¸ablonul se elimin˘
s s a
dac˘a
min[s(i1 ), s(i2 ), . . . , s(ik )]
h − confidenta(X ) ≤ ≤ hc
max[s(i1 ), s(i2 ), . . . , s(ik )]
Valoarea peste hc a h-confidentei ne asigur˘ c˘ obiectele din multime
¸ a a ¸
sunt puternic corelate ˆ
ıntre ele
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