Page 66 - Programming With Python 3

An Introduction to STEM Programming with Python — 2019-09-03a Page 53
Chapter 4 — Collections of Data

Selected List Methods

List methods work differently than st
Free ring methods, they do not return new strings that you need to
assign to a variable or use. These methods actually change the list in memory, directly. You will get
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unusual results if you try to assign these back to the original list.

Append

The first method you need to know is .append(). It does exactly what you would expect a method with
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name to do, it adds a value (or a list of values) to the end of the list. In the example below we can see
that you have earned a 99% on a new assignment, and appended it to the list of grades.

list.append(expression) Method of List

Add a new item or list to the end of an existing list.
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1| Grades = [.89, .96, 1.00, .76]
2| grades.append(.99)
3| n = len(grades)
4| s = sum(grades)
5| print("With", n, "grades in the list you have an average
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of",s/n)

With 5 grades in the list you have an average of 0.92

Insert
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You may want to do more than append an item, especially in a list where order is important. To do this
we use the .insert() method. You will pass two values to insert: 1) the location to put the new value, and
2) the value to insert.

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