The document introduces software development concepts using Python, specifically focusing on lists, their creation, and manipulation techniques. Key points include the differences between lists and strings, accessing elements, and using various methods like append, pop, and remove on lists. The document also emphasizes that Python lists can store mixed types and supports multidimensional lists.

1. An Introduction To Software
Development Using Python
Spring Semester, 2015
Class #9:
Lists, Part 1

2. Python Is All About Lists
• What lists do you use in your life today?
• Polytech Florida Common Prerequisites list of
classes: Course ID, Course Name, Course Credits
CHM 2045,Chemistry 1,3
CHM 2045L,Chemistry 1 Laboratory,1
COP 2271c,Introduction to Computation and Programming,3
EEL 3111c,Circuits 1,4
EEL 3112c,Circuits 2,3
MAC 2311,Analytic Geometry and Calculus 1,4
MAC 2312,Analytic Geometry and Calculus 2,4
MAC 2313,Analytic Geometry and Calculus 3,4
MAP 2302,Differential Equations,3
PHY 2048,Physics 1,3
PHY 2048L,Physics 1 Laboratory,1
PHY 2049,Physics 2,3
PHY 2049L,Physics 2 Laboratory,1
Image Credit: Clipart Panda

3. 4 Steps To Creating A Python List
1. Convert each of the names into strings by surrounding the
data with quotes.
2. Separate each of the list items from the next with a comma.
3. Surround the list of items with opening and closing square
brackets.
4. Assign the list to an identifier (movies in the preceding code)
using the assignment operator (=).
“COP 2271c” “Introduction to Computation and Programming” 3
“COP 2271c”, “Introduction to Computation and Programming”, 3
[“COP 2271c”, “Introduction to Computation and Programming”, 3]
prerequisites = [“COP 2271c”, “Introduction to Computation and Programming”, 3]
COP 2271c Introduction to Computation and Programming 3
Image Credit: Clipart Panda1

4. Python Is Different From Other
Programing Languages!
• Other languages (C, C++, Java, etc.) insist that every identifier used in code
has type information declared for it. Not so with Python: identifiers are
simply names that refer to a data object of some type.
char example1;
int example2 = 5;
void example3(void)
• One way to think of Python’s list is as a high-level collection.
• The type of the data items is not important to the list. All Python needs to
know is that you need a list, you’ve given it a name, and the list has some
data items in it.
Image Credit: Clipart Panda

5. What Does Your List Look Like
Inside Of The Computer?
COP 2271c
Introduction to Computation and Programming
3
0
1
2
Python
Starts
Counting
At 0
Each item in a list
has an index
number associated
with it…
prerequisites = [“COP 2271c”, “Introduction to Computation and Programming”, 3]
The computer stores
your list data in what is
called an “array”.

6. How To Access A List
• A list is a sequence of elements, each of which has an
integer position or index.
• To access a list element, you specify which index you
want to use.
• That is done with the subscript operator ([] ) in the
same way that you access individual characters in a
string.
• For example:
print(values[5]) # Prints the element at index 5
Image Credit: imgkid.com

7. Access Your List Data Using The
Square Bracket Notation
print (prerequisites[0]) COP 2271c
print (prerequisites[1]) Introduction to Computation and Programming
print (prerequisites[2]) 3
Image Credit: Clipart Panda2

8. You Can Create
Multidimensional Lists
• Lists can hold data of mixed type.
• But it gets even better than that: lists can hold
collections of anything, including other lists.
• Simply embed the inner list within the
enclosing list as needed.
multiDim = [[123],[456],[789]] =
1 2 3
4 5 6
7 8 9
Image Credit: www.rafainspirationhomedecor.com3

9. Programming Challenge
• How many credits need to be taken to satisfy
Poly prereqs?
Image Credit: www.clker.com4

10. Did You Know?:
Accessing A List Backwards
• Python, unlike many other languages, also
allows you to use negative subscripts when
accessing an element of a list.
• The negative subscripts provide access to the
list elements in reverse order.
• For example, a subscript of –1 provides
access to the last element in the list:
last = values[-1]
print("The last element in the list is", last)
Image Credit: lessonpix.com

11. What Is The Difference Between A
List And A String?
• Both lists and strings are sequences, and the [] operator can
be used to access an element in any sequence.
• There are two differences between lists and strings.
– Lists can hold values of any type, whereas strings are sequences of
characters.
– Moreover, strings are immutable—you cannot change the characters
in the sequence. But lists are mutable. You can replace one list
element with another, like this:
values[5] = 87
Image Credit: www.dreamstime.com

12. What Happens When You
Copy A List?
Image Credit: imgkid.com

13. Lists Are Much More Than Just
Simple Arrays
• Lists in Python are full-blown Python
collection objects.
• This means that lists come with ready-to-use
functionality in the form of list methods.
BIF
len
Methods
1. append
2. pop
3. remove
4. insert
5. extend
Image Credit: besttoddlertoys.eu

14. Playing With Lists: Append
• Add teacher: Dr. Jim Anderson
• Add year: 2015
Note: Python lists can contain data of mixed types. You can mix strings with
numbers within the same Python list. You can mix more than just strings and
numbers -- you can store data of any type in a single list.
prerequisites = [“COP 2271c”, “Introduction to Computation and Programming”, 3]
Image Credit: ClipArt Best5

15. Playing With Lists: Pop
• Allows you to remove the item that is at the
end of a list
prereqs[course].pop()
CHM 2045 , Chemistry 1 , 3 , Dr. Anderson , 2015
X
Image Credit: blog.poolproducts.com6

16. Playing With Lists: Remove
• Allows you to specify which list item you want
to remove no matter where in the list it is
located
prereqs[course].remove("Dr. Anderson")
CHM 2045 , Chemistry 1 , 3 , Dr. AndersonX
Image Credit: www.pinterest.com7

17. Playing With Lists: Insert
• Allows you to add an item to a list in a
specified location on the list
prereqs[course].insert(2,"Really Hard")
CHM 2045 , Chemistry 1 , Really Hard , 3
Image Credit: ekskavatör8

18. Playing With Lists: Extend
• Allows multiple list items to be added to an
existing list
prereqs[course].extend(["Dr. Anderson", "2015"])
CHM 2045 , Chemistry 1 , Really Hard , 3 , Dr. Anderson , 2015
Image Credit: www.clipartpanda.com9

19. What’s In Your Python Toolbox?
print() math strings I/O IF/Else elif While For
Lists

20. What We Covered Today
1. Lists
2. Multidimensional lists
Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/

21. What We’ll Be Covering Next Time
1. Lists, Part 2
Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/