Python notes list functions and methods use examples

Learn the difference between raw_input and input before learning the list: (Only for version 2, version 3, raw_input and input merge, no raw_input)

The syntax for input is: input ("str").

The Raw_input function saves all input as the original data in a string format;

The input Default user entry is a valid Python format and has some limitations when it comes to string connections.

1. Sequence Index

There are two types of expressions for a sequence index in Python:

(1) The first element index is 0, the second one is 1, and so on;

(2) The last element index is-1, the second to the bottom is-2, and so on;

Thus, assuming that the number of sequences A is n, then for the first element: A[i]=a[-n+i]

2. Sequence Shards

A shard is an extension of an index that accesses a single element, and the Shard accesses a range of elements. The Shard needs to provide two indexes as a boundary, the elements of the first index are contained within the Shard, and the second is not contained within a shard.

Example:

>>> number=[0,1,2,3,4,5,6,7,8,9]
>>> Number[2:5]
[2, 3, 4]

The representation of the step size:

>>> Number[2:9:2]
[2, 4, 6, 8]
>>> Number[2:8:2]
[2, 4, 6]

function: Len: The number of elements, and Min and Max return the smallest and largest elements in the sequence, respectively.

3. Basic list Operations

First introduce the list function: Split the string into an array format

>>> list ("list")

[' l ', ' I ', ' s ', ' t ']

(1) Element assignment:

>>> number=[0,1,2,3,4,5,6,7,8,9]

>>> number[0]=10
>>> number
[10, 1, 2, 3, 4, 5, 6, 7, 8, 9]

(2) Deleting an element

>>> number=[0,1,2,3,4,5,6,7,8,9]

>>> del Number[0]
>>> number
[1, 2, 3, 4, 5, 6, 7, 8, 9]

(3) Shard Assignment

>>> number[1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> number[0:]=[1,2,3]
>>> number
[1, 2, 3]

4. How to List

(1) Append: Add a new element at the end of the list

>>> number=[1, 2, 3]

>>> Number.append (5)
>>> number
[1, 2, 3, 5]

(2) Count: Count the number of occurrences of an element

>>> number=[1, 2, 3]

>>> Number.count (1)
1

(3) Extend: Adding a sequence after a sequence

>>> a=[1,2,3]
>>> b=[4,5,6]
>>> A.extend (b)
>>> A
[1, 2, 3, 4, 5, 6]

Python notes list functions and methods use examples