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![Getting back to PHP
We can use arrays to model the text. So,
within a FOREACH loop iterating through
the lines of a text and parsing each line for
“words,” we could do the following:
$words[$word]++;
$words[] = $word;
$lines[$lineNumber][] = $word;
Each method suggests a different model](https://image.slidesharecdn.com/mdst3705-2013-02-05-databases-130205124829-phpapp01/85/Mdst3705-2013-02-05-databases-8-320.jpg)
![More about PHP Arrays
• Arrays can be added to like so:
$myArray[] = $newItem;
• Arrays can also use strings instead of
number as indices, e.g.
$myArray[3] = „foo‟;
$myArray[„person‟] = „Bob‟;
• Array items may also point to arrays,
creating multidimensional arrays
$myArray[„person‟] = array();
$myArray[„person‟][„Bob‟] = $something;](https://image.slidesharecdn.com/mdst3705-2013-02-05-databases-130205124829-phpapp01/85/Mdst3705-2013-02-05-databases-9-320.jpg)
![Arrays as Data Structures
• PHP arrays can be used to create data
structures to model things, like texts, e.g.
$words[$word]++;
$words[] = $word;
$lines[$lineNumber][] = $word;
• These three create the following
1. A simple list of word types (and their
counts)
2. A list of each word in order (position and
word)
3. A grid of line numbers and words](https://image.slidesharecdn.com/mdst3705-2013-02-05-databases-130205124829-phpapp01/85/Mdst3705-2013-02-05-databases-12-320.jpg)
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Mdst3705 2013-02-05-databases
- 1. From Data Structuresto Databases Prof. Alvarado MDST 3703 5 February 2013
- 2. Business • Quiz 1 – To be posted this evening – Due Thursday evening – Covers content before Databases – End-of-week reflections still due • Blogging – Please remember to be timely • Safari Resources – If you can‟t access, try going through the Library page
- 3. Review • Building asknowing – Ramsay‟s point in “On Building” • DH as cultural reverse engineering – Finding the rules in the patterns – Texts and images are the patterns in question • Reverse engineering is like building – Same process in reverse (deconstruction) – Also requires building other things – like databases to store stuff
- 4. For example, inStudio on Thursday we began to reverse engineer Plato’s Republic. The next step in our exercise was to parse the text into “words” and organize them in a list using an array
- 5. By the way,were we actually grabbing words?
- 6. Not really –we were find substrings, letter patterns that could also exist within words (e.g. “cavern”) Also, these patterns did not match synonyms or pronouns (e.g. “this”) that stand for the same thing as the word in question This is the difference between SYNTAX and SEMANTICS
- 7. Syntax = sequencesof signs Semantics = meanings of signs Semantics is much harder for computers to grasp than syntax In fact, some think that semantics is beyond the capacity of any computer …
- 8. Getting back toPHP We can use arrays to model the text. So, within a FOREACH loop iterating through the lines of a text and parsing each line for “words,” we could do the following: $words[$word]++; $words[] = $word; $lines[$lineNumber][] = $word; Each method suggests a different model
- 9. More about PHPArrays • Arrays can be added to like so: $myArray[] = $newItem; • Arrays can also use strings instead of number as indices, e.g. $myArray[3] = „foo‟; $myArray[„person‟] = „Bob‟; • Array items may also point to arrays, creating multidimensional arrays $myArray[„person‟] = array(); $myArray[„person‟][„Bob‟] = $something;
- 10. Arrays with stringindices are called “associative arrays” in PHP Arrays of arrays can be used to create data structures like trees and grids
- 11. Read Chapter 5of PHP: The Good Parts to learn more about arrays (see link in Resources on the course blog) Also, the PHP manual is always a good place to look http://php.net/manual/en/language.types.array.php
- 12. Arrays as DataStructures • PHP arrays can be used to create data structures to model things, like texts, e.g. $words[$word]++; $words[] = $word; $lines[$lineNumber][] = $word; • These three create the following 1. A simple list of word types (and their counts) 2. A list of each word in order (position and word) 3. A grid of line numbers and words
- 13. Here is anexample of how we would create the third kind of data structure. This would store a grid of words.
- 14. These numbers arethe first dimension of the array (Y) These horizontal numbers are the second dimension of the array (Y) And it would store the text in grid something like this one …
- 15. In this model,a text is a grid of words, each with an X and Y coordinate Is this the only way to represent a text? Is it the most accurate?
- 16. Texts can alsobe represented as trees
- 17. Document Elements andStructures Play – Heading – Act + • Return Address • Scene + • Date – Line + • Recipient Info – Name Book – Title – Chapter + – Address • Verse + – Content • Salutation • Paragraph + • Closing Letter
- 18. XML is designedto represent text
- 19. What are somedifferences between trees and tables?
- 20. Tables are morerigid Trees allow for indefinite depth But tables are easier to manipulate In any case, tables and trees are two major kinds of data structure that you will encounter …
- 21. Speaking of trees… what is this?
- 22. Tree of Logic(and a primitive computer) ". . . the tree of nature and logic by the thirteenth-century poet, philosopher, and missionary Ramon Lull. The main trunk supports a version of the tree of Porphyry, which illustrates Aristotle's categories. The ten leaves on the right represent ten types of questions, and the ten leaves on the left are keyed to a system of rotating disks for generating answers. Such diagrams and disks comprise Lull's Ars Magna (Great Art), which was the first attempt to develop mechanical aids to reasoning. It served as an inspiration to the pioneer in symbolic logic, Gottfried Wilhelm Leibniz.” John Sowa, explaining the cover art for Knowledge Representation
- 25. What is thistree an example of?
- 26. The tree isa “knowledge representation” (KR)
- 27. A KR isa model that comprises 1. A set of categories (aka Ontology) Names and relationships between names 2. A set of inference rules (aka Logic) A method of traversing names and relations 3. A medium for computation A medium for producing inferences 4. A language for expressing these things Such as a programming or markup language
- 28. Ontologies are systemsof categories rooted in world views
- 29. Ontologies consist of categoriesand their relationships These are often mapped onto physical things – the human body, or trees – as part of our cognitive model
- 30. The tree asbody as society among the Umeda of New Guinea
- 31. Logic is aname for the systematic unpacking ontologies in discourse …
- 32. Here is asample ontology, one very similar to Aristotle’s
- 33. And this isa syllogism, the basic unit of reasoning in classical logic How is it related to the tree?
- 34. The sentences inthe syllogism stand for the traversal of the tree that represents an implicit ontology
- 35. Reasoning always impliesan ontology Ontologies are often unexpressed Ontologies often conflict with each other (Digital) Humanists excavate or reverse engineer these ontologies
- 36. Now, a KRfor a computer has to be an operationalized KR How would we express a syllogism in PHP?
- 37. One way isto convert the tree into an array
- 38. But, given suchan array, how can we find out if Socrates is mortal? How do we find if the following is set: 0 1 2 3 4
- 39. We’d have tosome some complicated nested looping to find the answer …
- 40. So, PHP givesus tools to create an ontology, but not a way to reason efficiently with them To create more effective KRs, we need the services of a database
- 41. A database isa “a system that allows for the efficient storage and retrieval of information” But beyond this, it also allows us to “represent knowledge” Given Unsworth‟s definition, how must it do this?
- 42. Databases provide alanguage to define ontologies (schema) and to “unpack” these ontologies – via a query language that lets us efficiently search and retrieve data organized schema
- 43. In this course,we are going to use a relational database to store and access information Relational databases use a language known as SQL (pronounced S-Q-L, although some say “sequel”)
- 44. SQL • SQL standsfor “Structured Query Language” – NOT invented by Microsoft • Invented in the 1970s and commercialized in the 1980s – Probably responsible for new business models like JIT inventories • Built on Codd‟s relational model (1970) – Implements set theory and formal logic – Around the time of SGML
- 45. SQL • A languageused by relational databases – Oracle, SQL Server, Access, etc.
- 46. MySQL • A veryfast, simplified, and easy to use relational database • A client/server app – Runs on the internet – Not a desktop app like Access • Created by Monty Widenius in the mid 1990s – Open Source – A Finn living in Sweden – Same time as PHP • Powered the Web 2.0 revolution
- 47. phpMyAdmin • A PHPinterface to MySQL • Relatively easy to use – No need to know SQL • Great to manage databases that your PHP programs will use • Today you will get started using UVA‟s free MySQL server
- 48. The role ofPHP