CS 105: TOPIC 10 – LISTS (ADVANCED) TOPIC 11 – HTML (NOT AS ADVANCED) Max Fowler (Computer Science) https://pages.github-dev.cs.illinois.edu/cs-105/web/ JULY 19, 2020
Week 6 Video Series Topics List Slices List Nesting List Comprehensions Some basic HTML
List Slicing
Slicing Lists Just like with strings, we can slice lists – they're collections! Same syntax my_list = [1,2,3,4,5,6] a_slice = [start_point:end_point] As before, the end is not included
As before… ml = [1,2,3,4,5] [1,2,3] new_slice = ml[:3] [3,4,5] ns_2 = ml[2:] [1,2,3,4,5] #but… copy = ml[:] copy == ml #True copy is ml #False
Video question You are asked to slice between the first and second 5 in the list a_list (including the 5s). What function lets you find the 5s? a_list = [1,2,5,4,2,5,1,1,2]
List Nesting
List Nesting Like with loops, we can nest lists Effectively a "list of lists" [[3,4,5], [1,2,3], [2,1,3]] This is where nested loops come in as useful too!
Element access A list of lists is like a table… al = [[1,2,3], [4,5,6], [7,8,9] 1 2 3 4 5 6 7 8 9 So what is al[1][1]?
Best with example, so… Coding example 1: Let's write a function which takes a list of lists. It should return the sum of ALL of the even numbers in the list
More examples! Coding example 2: Let's write a function which takes a list of lists. It should return the index of the sublist with the LARGEST sum
Video Question my_list = [ ['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i'] ] x = my_list[1][2] What is the value of x?
List Comprehensions
List comprehensions Syntactic sugar – write things more efficiently It's okay not to understand it…but it's pretty dope [expression for value in sequence] [expression for value in sequence if condition] I showed it off on one of the Wednesday class meetings
Two examples… Using a list comprehension, let's do the following: Write a function which, given a list, returns a version with all uppercase versions of each string Write a function which, given a list, returns the absolute value of ALL odd numbers in the list
No Video Question You may have list comp on homework for practice, but you can always use a regular loop to do the same things!!
What is HTML?
What is HTML? HTML is H yper T ext M arkup L anguage Not a programming language in the regular sense Describes web page content using HTML tags
What HTML interactions will you have in this class? Summer is fast…pretty late in the semester to have y'all code big web pages! You will have: A lab (at least one) Some parsons problems Some Python problems "writing" HTML tags as strings
Syntax Differences Between HTML & Python (20.2-3) Whitespace (spaces, tabs, newlines) Really important in Python. Ex: Optional, used just for clarity in HTML. Ex: both of these produce for item in list: Runs correctly same result: print(item) <ul> Versus <li>A list item.</li> <li>Another list item.</li> for item in list: print(item) </ul> Causes IndentationError <ul><li>A list item.<li><li>Another list item.</li></ul>
Syntax Differences Between HTML & Python (20.2-3) Comments HTML Python Use <!-- and --> for comments: Use # for single line comments: <p>A demonstration of # this is a comment comments</p> new_list = [“coconut”, “butter”, “flour”] <!-- This is a comment which can # this is another comment span over as many lines as we want. It only ends when the end comment Need # at beginning of every new notation is used. --> line of comments <p>The demonstration is over.</p>
Very Simple Web Page I thought it might be useful to show off making a simple web page I will do so in Notepad++ Will feature A header Bold and italic text an image
No Video Question Doesn't make sense to ask one about HTML, largely a side/interest topic
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