Python learning-list operations, python learning-list

Python learning-list operations, python learning-list

Python list Operation:

List creation and update:

1 # list Update 2 list = ['physics ', 'chemistry', 1997,2000] 3 print ('value available at index 2: ', list [2]) # The index of the list starts from 0 and is in turn 14 list [2] = 2001 # You can update the list by directly assigning values 5 print ('value available at index 2 :', list [2]) 6 7 # result: 8 # Value available at index 2: 19979 # Value available at index 2: 2001

Add elements to the list:

1 # Use append to add elements to the list. 2 list = ['physics ', 'chemistry'] 3 list. append ('wangtao') # Add the 'wangtao' 4 print (list [1]) 5 print (list) element to the list) 6 7 # result 8 # chemistry9 # ['physics ', 'chemistry', 'wangta']

Delete list elements:

1 # Delete list elements 2 list = ['physics ', 'chemistry', 1997,200 0] 3 print (list) 4 del list [1] # Use the del statement to delete the list elements 5 print (list) 6 7 # result 8 # ['physics ', 'chemistry ', 1997,200 0] 9 # ['physics ', 1997,200 0]

List OPERATOR:

1 # list operator 2 import operator 3 list = [1, 2, 3, 4, 5] 4 list2 = [2, 3, 4, 5] 5 print (len (list )) # len is used to obtain the length of the list 6 print (list + list2) # '+' combine the elements of the two lists into a list 7 print (list * 2) # '*' repeated list 8 print (3 in list) # determine whether the element is in the list 9 print (6 in list) # determining whether an element is in the list 10 print (max (list) # Return the maximum value of the element in the list 11 print (min (list) # Return the minimum value of the element in the list 12 print (operator. eq (list, list2 ))

1 # Some operator operations in Python 2 operator. lt (a, B) 3 operator. le (a, B) 4 operator. eq (a, B) 5 operator. ne (a, B) 6 operator. ge (a, B) 7 operator. gt (a, B) 8 operator. _ lt _ (a, B) 9 operator. _ le _ (a, B) 10 operator. _ eq _ (a, B) 11 operator. _ ne _ (a, B) 12 operator. _ ge _ (a, B) 13 operator. _ gt _ (a, B)

13 # There is no cmp function in python 3. To compare two list elements, call the operator Module 14 15 16 # result: 17 #518 # [1, 2, 3, 4, 5, 2, 3, 4, 5] 19 # [1, 2, 3, 4, 5, 1, 2, 3, 4, 5] 20 # True21 # False22 #523 #124 # True

List truncation:

1 # list capture 2 list = ['physics ', 'chemistry', 1997,200 0] 3 print (list [2]) # output index '2' element 4 print (list [-3]) # output the last and third elements 5 print (list [1:]) # output list element 6 7 from index '1' result: 8 #1997 9 # chemistry10 # ['chemistry ', 1997,200 0]

Other list operations:

1. list. append (obj): Add new objects 2 and list at the end of the list. count (obj): count the number of times an element appears in the list. 3. list. extend (seq): append multiple values in another sequence at a time at the end of the list (extend the original list with the new list) 4. list. index (obj): locate the index position of the first matching item of a value from the list. insert (index, obj): insert objects to list 6 and list. pop (obj = list [-1]): removes an element from the list (the last element by default) and returns the values of this element 7 and list. remove (obj): removes the first matching item 8 and list of a value in the list. reverse (): elements 9 and list in the reverse list. sort ([func]): sorts the original list.