"Turn" Python Learning (7)-List

Transfer from http://www.cnblogs.com/BeginMan/p/3153842.html

First, Sequence type operator

1. Slice [] and [:]

2. Member relationship operator (in, not in)

   1:  S1 = [1,2,3,4,5,6,7]

   2:  s2 = [2,3,6]

   3:  s3 = []

   4: In  S1:

   5: In       S2:

   6:           s3.append (obj)

   7:  

   8:  Print S3

   9:  s4 = set (S1)-set (S2)

  :  Print S4    #set ([1, 4, 5, 7])

3. Connection operator (+)

+: Connect the same type on both sides, and create a new object after the connection, cannot add an element in, can only be a list object +list object.

   1:  print s1+s2 #[1, 2, 3, 4, 5, 6, 7, 2, 3, 6]

   1:  Note:

   2:  li=[1,2,3]

   3:  li.extend (' good '),

   4:  print Li  outputs: [A/C, 'g ',' o 'o ',' d ']   

   5:  If we switch to Li.append (' good '), then the output is [",' good ']. 

   6:  This is because extend () adds an entire list object, append () adds an element

Attention:

   1:  >>> li = [+]

   2:  >>> li +' new item '

   3:  

   4:  Traceback (most recent):

   5: In    <module>

   6: Li +      ' new item '

   7:  "str") to list

   8:  >>> li.extend (' item ')

   9:  >>> li

  Ten:  ' m ']

  One:  >>> li.append (' item ')

  :  >>> Li

  :  ' item ']

  14:  

4. Repeat operator (*)

Ii. list type built-in functions

1. List.append (obj): Add an object to the list obj

   1:  lis = [1,2,3,4,' a ',' B ',' C ',' a ',' aaa ',' e ',' great ']   

   2:  lis.append (' object ')

   3:  print lis   ' object ']

2, List.count (obj): Returns the number of times an object obj appears in the list

   1:  #print lis.count (' a ')  #2

3. List.extend (SEQ): Add the contents of the sequence SEQ to the list

   1:  lis.extend (' seq ')   ' Q '] 

4, List.index (Obj,i=0,j=len (list)): Returns the K value of List[k]==obj, and the range of K is i<=k<j, otherwise throws ValueError exception

   1:  #print lis.index (' aaa ')  #8

5. List.insert (index,obj): Inserts the object obj at index number (two parameters required)

   1:  Lis.insert (1,' Z ')

   2:  print lis   ' great ']

6, List.pop (index =-1): Delete and return the object at the specified position, default is the last

   1:  print lis.pop ()     #great

   2:  print Lis.pop (1)    #2

7. List.remove (obj): Remove object from list obj

   1:  lis = [1,2,3,4,' a ',' B ',' C ',' a ',' aaa ',' e ',' great ']     

   2:  #lis. Remove (' value ')

   3:  #如果不存在则发生异常:

   4:  #Traceback (most recent):

   5:  # in  <module>

   6:  #    Lis.remove (' value ')

   7: In  list

   8:  lis.remove (' a ')

   9:  ' great ']

  Ten:  lis.remove (' e ')

  One:  

  :  Print Lis

8, List.reverse (): In-situ flip list

   1:  lis = [1,2,3,4,' a ',' B ',' C ',' a ',' aaa ',' e ',' great ']     

   2:  lis.reverse ()

   3:  print lis   #[' A ', 4, 3, 2, 1]

9, List.sort ()

   1:  lis = [1,2,3,4,' a ',' B ',' C ',' a ',' aaa ',' e ',' great ']     

   2:  #lis. Sort (Cmp=none, Key=none, Reverse=false)

   3:  lis.sort (Cmp=none, Key=none, Reverse=true)

   4:  print lis   #[' A ', 4, 3, 2, 1]

Note: The method of changing objects that can change the value of an object is not a return value.

Such as:

   1:  lis = [1,2,3,4,' a ',' B ',' C ',' a ',' aaa ',' e ',' great ']     

   2:  print lis.extend (' MM ')  #None

   3:  result = Lis.extend (' MM ')

   4:  print result    #None

These operations perform operations on the list, meaning that the existing list contents are changed, but there is no return value. In contrast, the string method has a return value:

   1:  ' abc '. UPPER () #ABC

Where the built-in functions related to the sequence can have a return value:

   1:  print reversed (LIS)     object at 0x0128dad0>

   2:  print sorted (LIS)       ' great '

Third, sequence type function

1, Len ()

2, Max () min ()

3, sorted (), reversed (): Note that strings are sorted using a dictionary order instead of alphabetical order

4, enumerate (), Zip ()

See: http://www.cnblogs.com/BeginMan/archive/2013/03/14/2959447.html

5. SUM ()

6, List (), tuple ()

"Turn" Python Learning (7)-List