Python array, some operations of the dictionary

Beginners have just begun to learn python, if there is wrong or write bad place, please give us a lot of advice!
Output the current system in Python
Import Sys
Print (Sys.platform)
The output is currently in that directory
Import OS
OS.GETCWD ()
How many bits of a variable are output
s = ' spam '
Len (s)
Replace the value of a variable
s = ' Z ' + s[1:]
Find values within a variable
S.find (' pa ') #找到会返回1, could not be returned-1
Temporarily modify the value of a variable
S.replace (' pa ', ' xzc ') #将变量内pa临时替换成XZC
To run a file using exec
EXEC (open (' a.py;). Read ()) #能运行文件的最新版本
Python calculates the number of digits of a numeric value
Len (STR (2 * * 1000))
Python generates random numbers
Import Random
Random.random ()
Specify a range for the resulting random number
Random.random ([1,2,3,4])
Take out a place that fits into a division
A = ' aa,bb,cc,dd '
A.split (', ')
Remove the middle value at what begins with what ends
Import re
Match = Re.match (' hello[\t]* (. *) world ', ' Hello Python world ')
Match.group (1) #不匹配开头和结尾的值放到了group里边
Match = Re.match ('/(. *)/(. *)/(. *) ', '/usr/local/num ')
Match.Groups () #取出来/, show other values

List sequence Actions
Insert at last edge of array
L = [123, ' abc ', 1.23]
L.append (' ni ')
L.extend ([up])
L.insert (1, ' hello ') #在一的位置插入
To delete a value in an array
L.remove (123) #删除的时候要指定数值
L.pop (2) #python中的数组是从0 1 2 3 in this order
Del L[1] #删除第一位
Ascending order of arrays
m = [' 2 ', ' 3 ', ' 4 ', ' 1 ']
M.sort ()
Descending arrangement
m = [' 2 ', ' 3 ', ' 4 ', ' 1 ']
M.reverse ()

Array nesting
A =[[1,2,3],[4,5,6],[7,8,9]]
M[0][2] #结果输出3, reading the 2nd value in the first array

Python dictionary
D = {' Spa ': 2, ' Ham ': 1, ' Eggs ': 3}
Len (d) #查看d字典有几组值
Modify the value of a callout
d[' ham '] = [' Girl ', ' bak '] #在d数组中的修改ham的标注值
View dimension values only, and arrange them in reverse order
List (D.values ())
View all values of D
List (D.items ())
View callouts for a single point value
D.get (' Ham ') #只输出ham的标注
When a single point value does not exist
D.get (' aaaaa ', #当aaaaa不存在的时候), output 88
Dictionaries can be used to insert values in an updated way
D1 = {' Tom ': 4, ' Mum ': 5}
D.update (D1)
The deletion of the dictionary is the same
D.pop (' mum ') #如果 () If there is no content, the last one is deleted by default
You can specify the location of the character to delete
D.pop (1) #删除d组中的第二个值字典的排序是按照 0 1 sort of
A Python read dictionary can also be read in a variable way.
A = ' Spa '
b = d[a] #然后输出b的值就等于输出d字典中的 ' Spa ' value

Python specifies a dictionary that can be used to formulate
D = {}
D[99] = ' Spa '
d[' ham '] = 98
d[' lol '] = ' olk ' #新加的默认在最前边
Use if to detect whether the value is in the dictionary
if (' lol ') in D:
Print (d[(' lol ')])
Else
Print (0)
Insert a dictionary in the form of a zip function
D = dict (Zip ([' A ', ' B ', ' C '],[1,2,3])) #分别给相对应的位置来赋值a1 B2 C3.
Use for loops to assign values
D = {k:v for (k,v) in zip ([' A ', ' B ', ' C '],[1,2,3])}
operator &for loop to insert Dictionary
D = {X:X * * 2 for x in [1,2,3,4]}
D = {C:C * 4 for C in ' Spam '}
d= {c:c + '! ' for C in [' Spa ', ' ham ', ' DD ']} #在这里它默认会按照字母的顺序进行排列
Insert in a dict way
D = dict (a=1,b=2,c=3)
Remove the identity from the dictionary
K = D.keys ()
List (k)
Remove the dictionary value without the identity
v = d.values ()
List (v)
If you delete the values in the D dictionary, the values in K & V are removed.
Del d[' B ']
List (v)
List (k)
Novice has just begun to learn, if there is a wrong place, please give us a lot of advice!

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Python array, some operations of the dictionary