5.29. Group Work: Functions and Lists

It is best to use a POGIL approach with the following. In POGIL students work in groups on activities and each member has an assigned role. For more information see https://cspogil.org/Home.


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Learning Objectives

Students will know and be able to do the following.

Content Objectives:

Process Objectives:

5.29.1. List Indexing

A list holds items in order and you can get the value at an index, just like you can with strings.

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Q-8: Describe in your own words how negative indices work.

5.29.2. Built-in Functions That Work on Lists

There are several built-in functions in Python that work on lists.

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Write a function avg_with_drop that takes a list, num_list and returns the average of the values in the list, but it does not include the highest or lowest value in the average. For example, avg_with_drop([1,2,3,4]) should return 2.5.

5.29.3. List Methods

Lists are objects of the list class and have methods that operate on list objects.

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Lists are mutable (changeable). List methods like append and pop change the current list.

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5.29.4. Using the Slice Operator

You can use the slice operator[n:m] with lists to get a new list just like you can with strings.

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Q-20: In [2:] what is the end index?


The slice operator always returns a new object. It doesn’t change the current object (list or string).

Write a function first_half that takes a list and returns a new list (use the slice operator) with just the items from the first half of the original list. For example, first_half([1,2,3,4]) would return [1, 2] and first_half([7,8,9]) should return [7].

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