3.1.4.8 Lists - collections of data | list methods

Adding elements to a list: append() and insert()

A new element may be glued to the end of the existing list:

list.append(value)

Such an operation is performed by a method named append(). It takes its argument's value and puts it at the end of the list which owns the method.

The list's length then increases by one.

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The insert() method is a bit smarter - it can add a new element at any place in the list, not only at the end.

list.insert(location, value)

It takes two arguments:

• the first shows the required location of the element to be inserted; note: all the existing elements that occupy locations to the right of the new element (including the one at the indicated position) are shifted to the right, in order to make space for the new element;
• the second is the element to be inserted.

Look at the code in the editor. See how we use the append() and insert() methods. Pay attention to what happens after using insert(): the former first element is now the second, the second the third, and so on.

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Add the following snippet after the last line of code in the editor:

numbers.insert(1, 333)

Print the final list content to the screen and see what happens. The snippet above snippet inserts 333 into the list, making it the second element. The former second element becomes the third, the third the fourth, and so on.

•  Sandbox

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numbers = [111, 7, 2, 1]

print(len(numbers))

print(numbers)

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numbers.append(4)

print(len(numbers))

print(numbers)

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numbers.insert(0, 222)

print(len(numbers))

print(numbers)

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• Console