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Python list (Lists)

Python sequence is the most basic data structure. Each element in the sequence is assigned a number - its position, or index, the first index is 0, the second index is 1, and so on.

Python has a built-in type 6 sequences, but the most common are lists and tuples.

A sequence of operations can be carried out, including indexing, slicing, add, multiply, check members.

Further, Python already has built-in methods for sequence length, the maximum and minimum element. You may like this Python course


Python list is one of the most common types of data. It appears as a comma-separated values ​​in square brackets.

Create a list, as long as the comma-separated data items using different brackets can be as follows:

>>> list1 = [ 'physics', 'chemistry', 1997, 2000]
>>> list2 = [1, 2, 3, 4, 5]
>>> list3 = [ "a", "b", "c", "d"]

Like string indices, list indices start at 0. The list can be intercepted, combinations and the like.

Access list values

The index is used to access the values ​​in the list, as follows:

>>> list1 = [ 'physics', 'chemistry', 1997, 2000]
>>> list2 = [1, 2, 3, 4, 5]
>>> print(list1[0])
>>> print(list2[0])
>>> print(list1[1:3])
['chemistry', 1997]
>>> print(list2[1:3])
[2, 3]

update list

You can modify or update data items in the list, you can also add a list item using append() method, as follows:

>>> list1 = [ 'physics', 'chemistry', 1997, 2000]
>>> list1[2] = 2010
>>> list1
['physics', 'chemistry', 2010, 2000]
>>> list1.append("Tango")

Delete list elements

You can use the del statement to delete the list of elements, the following examples:

>>> list1 = [ 'physics', 'chemistry', 1997, 2000]
>>> list1
['physics', 'chemistry', 1997, 2000]
>>> del list1[1]
>>> list1
['physics', 1997, 2000]

Python script operator list

Similar lists of + and * operators string. + Number combination for the list, the list for repeatedly asterisk.

As follows:

Python expressions result Description
len ([1, 2, 3]) 3 length
[1, 2, 3] + [4, 5, 6] [1, 2, 3, 4, 5, 6] composition
[ 'Hi!'] * 4 [ 'Hi!', 'Hi!', 'Hi!', 'Hi!'] Repeat
3 in [1, 2, 3] True element exists in the list
for x in [1, 2, 3]: print x, 1 2 3 iteration

Python interception list

Python list operation type string taken as follows:

    L = [ 'spam', 'Spam', 'SPAM!']


Python expressions result Description
L [2] 'SPAM!' Third element in the list is read
L [-2] 'Spam' penultimate read list element
L [1:] [ 'Spam', '! SPAM'] taken from the second list element start

Python list of functions & methods

Python includes the following functions:

No. function
1 cmp(list1, list2) Compare the two lists of elements
2 len(list) The number of list elements
3 max(list) Returns a list of elements of the maximum
4 min(list) Returns a list of elements of the minimum
5 list(seq) Convert a list of tuples

Python includes the following methods:

No. Methods
1 list.append(obj) Add new object at the end of the list
2 list.count(obj) The number of times an element statistics appear in the list
3 list.extend(seq) A plurality of values ​​in another sequence added at the end of the list of one-time (with a new list of the original extended list)
4 list.index(obj) A value index to find the location of the first match from the list
5 list.insert(index, obj) Inserting objects list
6 list.pop(obj = list [-1]) Removing one element in the list (default to the last element), and returns the value of the element
7 list.remove(obj) Remove the list a value of the first match
8 list.reverse() Reverse elements in the list
9 list.sort([func]) The original list is sorted

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