1. Sample lecture slides

2. Python: basic data types
Numbers (done)
Strings
Lists
Dictionaries

3. Strings

4. Python: basic data types
Numbers
Strings
Lists
Dictionaries

5. Python Lists Recall strings from last time?
Think of those as lists too

6. Python Lists vs. Sets set is faster than list for lookup (hashtable)
in – membership
not in – not a member of
set(List) - produces a set, no duplicates permitted
set is faster than list for lookup (hashtable)

7. Python Lists

8. Python Lists Lists as stacks Lists as queues
Lists as stacks
Lists as queues
List Comprehensions (advanced topic)

9. Python List as a Queue Method append() to add to the queue
list[0] gives us the head of the queue
list = list[1:] deletes the head of the queue from the queue
EXAMPLE:

10. Python https://docs.python.org/3/tutorial/introduction.html Numbers
Strings
Lists
Dictionaries

11. Python Lists Lists as stacks Lists as queues
Lists as stacks
Lists as queues
List Comprehensions (advanced topic)

12. Python List as a Queue Method append() to add to the queue
EXAMPLE:
Method append() to add to the queue
list[0] gives us the head of the queue
list = list[1:] deletes the head of the queue from the queue
Also can use del list[0]

13. Python List as a Queue
A faster implementation according to section 5.1.2

14. Python List as a Stack
pop() removes from the same end as append()

15. Tuples See use with dictionaries later …
Section 5.3: note instead of square brackets, round brackets are used
See use with
dictionaries
later …

16. Dictionaries (dict)
Lists and tuples are indexed by whole numbers (from 0)
Dictionaries are indexed by a key (usually a string) and return some value associated with the key
Note: use of curly braces
Dictionaries are not ordered (like sets) – see next slide
Methods keys(), values(), items()
Refer to key + value as an item: encoded as a tuple

17. Dictionaries (dict)
Example from class…

18. Dictionaries (dict) Python 3.6
Dictionary order preservation depends on the version of Python used …
Python 3.6

19. Dictionaries (dict) How to print the contents of a dictionary?
Use a for-loop and method items(): k,v is a tuple

20. Dictionaries (dict) All values are lists
Advantage: simplifies the code
Trade-off
Values are lists or a string
Advantage: simpler-looking dict

21. Dictionaries Works too! Less transparent: relies on a
Python-particuar quirk …

22. Dictionaries (dict)
function zip() pairs up elements from two lists into an iterable

23. Dictionaries (dict)
function zip() doesn't always work quite the same …

24. For loops and range()
range(start,stop,step) returns an iterable that can be used with a for- loop
range(stop) start assumed to be 0; step assumed to be 1; range does not include stop

25. For loops and range() Ranges can be indexed like a list
Can use in and not in