Python Language List

Internal

• Python Language

Overview

A list is a mutable sequence type that contains zero or more elements and whose elements can be of different types.

List type()

The function type() applied to a list returns: <class 'list'>

To check whether an instance is a list:

i = ...
if type(i) is list:
  ...

For list subclasses:

i = ...
if isinstance(i, list):
  ...

Access to a List

Size of a List

The number of elements is given by the len() function:

l = [...]
print(len(l))

Modify a List

Modify Individual Elements

Append an Element

l.append(e)

Delete the Last Element

del l[-1]

Assign the sublist to l:

l = l[:-1]

List Processing

Join the List Elements in a String

Join the elements of the given list in a string, using '-' as separator:

li = ['a', 'b']
s = '-'.join(li)

Only works if the list elements are strings.

Extract Elements Starting with a Certain Index

l = [1, 2, 3]
print(l[0:]) # prints [1, 2, 3]
print(l[1:]) # prints [2, 3]
print(l[2:]) # prints [3]
print(l[3:]) # prints [] (empty list)
print(l[4:]) # prints [] (empty list)