Python Language List: Difference between revisions
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A list is a mutable [[Python_Language#Sequence_Types|sequence type]] that contains zero or more elements and whose elements can be of different types. | A list is a mutable [[Python_Language#Sequence_Types|sequence type]] that contains zero or more elements and whose elements can be of different types. | ||
=List <tt>type()</tt>= | =List <tt>type()</tt>= | ||
The function <code>type()</code> applied to a list returns: | The function <code>type()</code> applied to a list returns: | ||
<font size=-1> | <font size=-1> | ||
Line 24: | Line 23: | ||
... | ... | ||
</syntaxhighlight > | </syntaxhighlight > | ||
=Create a List= | |||
=Access a List= | |||
=Modify a List= | |||
=Access to a List= | =Access to a List= |
Revision as of 22:56, 6 March 2022
Internal
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):
...
Create a List
Access a List
Modify a List
Access to a List
Size of a List
The number of elements is given by the len()
function:
l = [...]
print(len(l))
Iterate over a List
l = ['A', 'B', 'C']
for i, e in enumerate(l):
print(f'index: {i}, element: {e}')
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]
Delete All Elements
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 from the Tail of the List 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)
Extract Elements from the Head of the List Counting from the Tail
TODO