Python Next day Study summary

1. Detailed Data types
int: integral type, for example: 1,4,100 ..... Mainly used to calculate
STR: String. Primarily used to store small amounts of data
List: Storing large amounts of data
Tuple: Similar to list, is a read-only list
Dict: Storing relational data
BOOL: Boolean indicating True and False

2.str
In Python, quotation marks (single quotes, double quotes, and three quotation marks) are all caused by strings.
name = ' CC '
Name = "CC"
info = ""
Name:cc
Age:18
‘‘‘
A. Adding strings
S1 = ' Hello '
S2 = ' CC '
Print (S1 + s2) #输出hellocc

B.strint
Print (' CC '3) #输出cccccc

C. Index and slice
s = ' dick and Harry cc '
S1 = s[0] #s1依然是str类型
Print (S1) #输出张, left-to-back (0 1 2 3 ...)
Print (s[-1]) #输出c, right-to-left values (-1 -2-3-4-5 ...)
Print (s[-3]) #输出四, right-to-left values (-1-2-3-4-5 ...)
Print (S[0:2]) #输出张三, the slice Gu Tou regardless of the tail, [Start index: End index + 1: Step]
Print (s[0:]) #输出张三李四cc
Print (S[0:4:2]) #输出张李,: 2 is the step size, the default step is 1, Go forward without the default step
print (s[-1:-5:-1]) #输出cc四李, reverse fetch, with reverse step-1
Print (S.find (' three ')) #输出1, index by element, and index usage, Find can not find the reference when the return -1,index will not find the value will be error

D. String manipulation
s = ' Zcchello ' s1 = ' zcc Zhangsan. Lisi9wangwu ' s3 = ' zcchello\t\n ' s4 = ' Zcc,zhangsan,lisi,wangwu '
S5 = [' zcc ', ' Zhangsan ', ' Lisi ', ' Wangwu ']
Print (S.capitalize ()) #字符串首字母大写其余小写, Output Zcchello
Print (S.swapcase ()) #大小写翻转, Output Zcchello
Print (S1.title ()) #非字母隔开的单词首字母大写, output zcc zhangsan.lisi9Wangwu
Print (S.center ()) #设置总长度为15并居中显示to fill, the default padding is a space
Print (S.upper ()) #全部变成大写, output Zcchello, for verification code
Print (S.lower ()) #全部变成小写, Output Zcchello
Print (S.startswith (' z ')) #判断是否以z开头, Output True
Print (S.endswith (' l ')) #判断是否以l结尾, output false
Print (S3.strip ()) #默认去除字符串前后的空格, newline, tab, and input combined, you can also specify the symbol to be removed or only remove the front (Ltrip) Back (Rtrip), Output Zcchello
Print (S.replace (' zcc ', ' Zhangsan ')) #替换, Output Zhangsanhello
Print (S4.split (', ')) #字符串分割成list, the default is a space-delimited, can specify delimiter, output [' zcc ', ' Zhangsan ', ' Lisi ', ' Wangwu ']
Print (". Join (S5)) #列表转换成字符串, output zcc Zhangsan Lisi Wangwu
Print (len (s)) #测量长度, output 8
Print (S.count (' C ')) #计数c出现的次数, Output 2

3.list
L1 = [3,4], 5,6] L2 = [' Zhangsan ', ' John Doe ', ' cc '] l3 = [1,4,7,8,9,0,3]
########### #查找值
Print (L1[2],type (l1[2))) #输出 (3, 4) <class ' tuple ' > values by index, consistent with the data type of the element itself
Print (L1[0:3],type (l1[0:3)) #输出 [1, 2, (3, 4)] <class ' list ' > by slice, take out a small list
For I in L1:
Print (i) #for循环取值
########## #list增加值
L2.append (' Harry ')
Print (L2) #输出 [' Zhangsan ', ' John Doe ', ' cc ', ' Harry '] append () Append value for list
L2.insert (1, ' Harry ')
Print (L2) #输出 [' Zhangsan ', ' Harry ', ' John Doe ', ' cc '] Insert values can be inserted according to the index
L2.extend ([i])
Print (L2) #输出 [' Zhangsan ', ' John Doe ', ' cc ', 1, 2, 3] extend for adding values that can be iterated
######### #list删除值
L2.pop (1)
Print (L2) #输出 [' Zhangsan ', ' cc '] pop () can be deleted by the index of the list
L2.remove (' cc ')
Print (L2) #输出 [' Zhangsan ', ' John Doe '] remove () can be deleted by the list element
L2.clear ()
Print (L2) #输出 [] Clear () empty list
Del L2[0:2]
Print (L2) #输出 [' CC '] del can be deleted by slice or index, or you can delete list
############# #改变值
L2[0] = ' Zhang San '
Print (L2) #输出 [' Zhang San ', ' John Doe ', ' CC '] can be modified by the index of the corresponding value
L2[0:2] = ' abc '
Print (L2) #输出 [' A ', ' B ', ' C ', ' CC '] can be modified according to the slice, slice is a space, can be re-added any value, if there is a step, must be one by one corresponding
############# #其余方式
Print (len (L1)) #输出5 Len () calculates the total number of list elements
Print (L2.count (' cc ')) #输出1 count () calculates the number of occurrences of an element
L3.sort ()
Print (L3) #输出 [0, 1, 3, 4, 7, 8, 9] sort () for positive ordering
L3.sort (Reverse=true)
Print (L3) #输出 [9, 8, 7, 4, 3, 1, 0] reverse order
L3.reverse ()
Print (L3) #输出 [3, 0, 9, 8, 7, 4, 1] Flip

4.tuple
A tuple is a read-only list that operates like a list

5.dict
DIC = {
' Name ': ' CC ',
' Age ': ' 28 ',
' Sex ': ' Male ',
}
############### #增加值
dic[' high ' = #增加 ' high ': 170
dic[' name '] = ' Zhang San ' # ' cc ' becomes ' Zhang San ' without adding, there is modification
Dic.setdefault (' High ', in #增加 ' High ': 170
Dic.setdefault (' name ', ' Zhang San ') #无任何修改 no increase, there is no change
############### #删除值
Dic.pop (' sex ') #删除 ' sex ': ' Male ' if there is no key to delete, you can specify the relevant return value
Dic.clear () #清空
Del dic[' name '] #删除 ' name ': ' CC ' can also delete the entire dictionary
############### #查询
Print (dic[' name ']) #输出cc query According to key, if there is no corresponding key error
Print (Dic.get (' name1 ', ' no Key ')) #get () query can specify the return value without the corresponding key
Print (Dic.keys ()) #查询所有的key放到一个容器中
Print (Dic.values ()) #查询所有的value
Print (Dic.items ()) #查询所有的 key and value

Python Next day Study summary