Basic 02 Basic data types for the Python Progressive Tutorial series

List features:

• An ordered set

• Index by offset to read data

• Nesting support

• Variable type

2. Slice

   Forward index (left-to-right):

   >>> a = [1,2,3,4,5,6,7]
   >>> A[0:4:1] # 1 is the step
   [1, 2, 3, 4]

   Reverse index:

   >>> A[-1:-4:-1] (right-left
   )
   [7, 6, 5]
   >>>
   

   Default index:

   >>> a[1:]
   [2, 3, 4, 5, 6, 7]
   

4. Adding actions to a list

   >>> a = [1,2,3,4]
   >>> B = [5,6,7,8]
   >>> A + b
   [1, 2, 3, 4, 5, 6,7,8] # Generate a new list
   >>>
   Extend: Takes a parameter and adds each element of the parameter to the original list, modifying the list in place instead of creating a new list

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

   Append: Add any object to the end of the list
   

   >>> a = [+ +]
   >>> A.append (4)
   >>> A
   [1, 2, 3, 4]
   
   >>> a.append ([3,4,5])//Insert List
   >>> A
   [1, 2, 3, 4, [3, 4, 5]]

   
   Insert: Inserts any object into the list to control the insertion position.
   [1, 2, 3, 4, [3, 4, 5]]
   >>>
   >>> A.insert (1, "abc")
   >>> A
   [1, ' abc ', 2, 3, 4, [3, 4, 5]
   
   

6. Modify actions for a list

   Modifying the list itself requires only the direct assignment of the action.

   >>> a = [+ +]
   >>> a[1]= ' Test '
   >>> A
   [1, ' Test ', 3]

8. Delete operation

   Del: We delete the element at the specified location by index

   >>> a = [1,2,3,4,4]
   >>> del A[0]
   >>> A
   [2, 3, 4, 4]
   

   Remove: Removes the first matching value from the specified value in the list. If it is not found, an exception will be thrown.

   >>> A
   [2, 3, 4, 4]
   >>> A.remove (4)
   >>> A
   [2, 3, 4

   Pop: Returns the last element and removes it from the list.

   >>> a = [1,2,3,4,5,6,7]
   >>> A.pop ()
   7
   >>> A
   [1, 2, 3, 4, 5, 6]

10. List member relationships

    In no in we can determine whether an element is in the list, return a bool type, if True is in the lists, and vice versa.

    >>> a = [+ +]
    >>>
    >>> 2 in a
    True
    >>> 5 in a
    False
    >>> 5 Not in a
    True
    >>>

12. List derivation

    1. First iterate all the contents of iterable, each iteration, put the corresponding content in the iterable into the Iter_var, and then apply the content of the Iter_var in the expression, Finally, a list is generated with the calculated value of the expression.
    
    than we're going to generate a list containing 1 to 10

    >>> [x  for x in range (1,11)]
    [1, 2, 3, 4, 5, 6, 7, 8, 9, ten]
    >>
    2. Added the judgment statement, only satisfies the condition content to put in the iterable the corresponding content in the Iter_var, then applies the content of the Iter_var in the expression, and finally generates a list with the calculated value of the expression.
    
    to generate all the odd list of numbers from 1 to 10.

    Range (1,11,2)
    >>> Range (1,11,2)
    [1, 3, 5, 7, 9]
    >>>

14. Sort Flip: Sort,reverse

    Sort: Modifies the original list directly, and its return value is None

    >>> a = [33,11,22,44]
    >>> B = A.sort ()//none
    >>>
    >>> b
    >>> if B is None:
    ... print ' haha '
    >>> if B is None:
    ... print ' haha '
    ...
    haha

    Reverse function: Reverses a list, and its return value is None

    >>> A
    [11, 22, 33, 44]
    >>> B = A.reverse ()
    >>> b
    >>> A//Direct view a list variable can see the effect of flipping
    [44, 33, 22, 11]
    >>>
    

This article is from "Never give up!" "Blog, be sure to keep this provenance http://rockyjun.blog.51cto.com/8504719/1544886

Basic 02 Basic data types for the Python Progressive Tutorial series