Python Basic Data type operation

Python comments

当行注视：# 被注释内容
多行注释：""" 被注释内容 """

String manipulation

# represents a single-line comment
s="Hello"
Print (s*2)#hellohello
Print (s[2:])# Llo, slice operation, cut from subscript 2 to last
PrintAIn s)#False

A=' 123 '
b=' ABC '
C=a+b#字符串拼接, poor efficiency, not recommended
#内置方法 join () high efficiency, advancing use
D='----'. Join ([A, b])# 123----ABC,


st="Hello\t kitty {name} is {age}"
St.count (' L ')#统计个数
Print (St.capitalize ())#首字母大写 Hell
Print (St.center (50,‘-‘))#放到中心, 50 Delegates '
#-----------HEllo Kitty {name} i
Print (St.ljust (50,‘-‘))#居左 HEllo
Print (St.rjust (50,‘-‘))#居右-------

Print (St.endswith (' Y '))#以什么结尾
Print (St.startswith (' He '))#以什么开头
 
Print (St.find (' V '))#查找第一个元素的索引, not for--

Print (St.format (name=' Alex ', age=37)
Print (St.format_map ({' Name ':' Alex ',
Print' 2 '. IsDigit ())#是否为整数
#print (St.index (' QQQ ')) #查找第一个元素的索引没
Print' abc456# '. Isalnum ())#是否是数字跟字符
Print' abc '. ISALPHA ())#是否为字母
Print' 123 '. Isdecimal ())#是否为十进制, basically not
Print' 1234 '. IsNumeric ())#是否为整数
Print' AsdA '. Islower ())#是否为小写
Print' AsdA '. Isupper ())#是否为大写
Print"". Isspace ())#是否是空格 (one or more)
Print ' Abn Av '. Istitle ())  #每一个首字母是否大 
  print (St.lower ())  #所有大写变小写 
  print (St.upper ())  #所有小写变大写 
  Print ( ' AB '. Swapcase ())  #大写变小写, lowercase to uppercase   
  print (   AAA   a\nbbb\n. Strip ())  # 
 St.lstrip ()  #去左                      
 St.rstrip ()  #去右                      
  print ( ' ASADFG '. Replace ( ' a ',  ' one ', 1)) 
  print ( ' 2234562 '. RFind ( ' 2 '))  #从右开始找, return 
  print ( ' a b C '. Split ( '))  #字符串的变为列表 * 
  print ( ' a b C '. Rsplit ( ", 1))  #从右开始有几 
  print ( ' AA BA cs '. Title ())  #将首字母都变为大写           

List operations

A = ["Xiaohu","Sanpang","Jinxin","Daling","Xiaoguo"]
#查
Print (a[1])
Print (a[1:4])#切片取, before the package
Print (a[1:])#取到最后
Print (a[1:-1])#取到倒数第二个
Print (a[1::2])#步长为2个, the step has direction
Print (a[3::-2]) #步长为2个, Step has direction 
 print (a[-2:: -1])    #-= Countdown 
 
  #增 Insert Append 
 A.insert ( 1,  "Xiaowang") 
 
  #修改 
 a[ 1]=  "AAA" 
 a[ 1:  3]=[ "ss ", " ww "] 
 
 
  #删除remove pop del 
 A.remove (" Xiaohu ")  #只能删一个对象 
 B=a.pop ( 0)  #返回删除的结果 
  del a[ 3]  #可删任何东西, including a object 
  #count计算列表里元素出现的次数 
 t = [ "a",  "A",  "B"].count ( "a") 
 
 Merge 
 a=[ 1,  2,  3] 
 b=[ 4,  5,  6] 
 A.extend (b)  #a改变了, b unchanged 
 C=a+b  #a, B does not change 
 print (A.index ( 1))  #返回第一个数据的值 
 
 Invert 
 A.reverse () 
 Sort 
 A.sort () 
 Print ( "AA"    in a)        

Tuple operations

查询
tup1 = (‘physics‘, ‘chemistry‘, 1997, 2000);
tup2 = (1, 2, 3, 4, 5, 6, 7 );

print "tup1[0]: ", tup1[0]
print "tup2[1:5]: ", tup2[1:5]

不允许修改元组，但我们可以对元组进行连接组合，如下实例:
tup1 = (12, 34.56);
tup2 = (‘abc‘, ‘xyz‘);

# 创建一个新的元组
tup3 = tup1 + tup2;
print tup3;

删除元组
元组中的元素值是不允许删除的，但我们可以使用del语句来删除整个元组，如下实例:
tup = (‘physics‘, ‘chemistry‘, 1997, 2000);
del tup;

Dictionary operations

#python中唯一的映射类型------Dictionary (unordered) is stored according to the hash algorithm
#id () #打印内存地址
#不可变类型: Shaping, string, tuple
#可变类型: List, dictionary
#字典的键必须为不可变类型, because it's the only
dict={' Name ':' Zhangqiye ',' Age ':' 11 ',' Sex ':' Nan '}
Print (dict[' Name '])
dict1={}
dict1[' Name ']=' Sanpang ' #可增加, can be modified

Dict1.setdefault (' Name ',' Wangwu ') #只可增加, can not be modified, there is a return value (return value in the dictionary)
Dict1.setdefault (' Age ',' 11 ')
 print (dict.  keys ()) #dict_keys ([ ' name ',    ' age ',    ' sex ']) 
  print ( Dict.  values ()) #dict_values ([ ' Zhangqiye ',    ' one ', '    ' nan ']) 
  print (Dict.  items ()) #dict_items ([( ' name ',    ' Zhangqiye '), ( ' age ',    ' one ') ', ( ' sex '),    ' nan ')] 
 dict2={ 1:  2, :  +} 
 Dict1.  Update (DICT2) 
  print (dict1) #{ ' name ':    ' Sanpang ',    ' age ':    ' 11 ',    1:   2,   22:   "
 #删除  del  clear    pop 
 Del dict[ ' name ' 
 #dict.  pop ( ' name ') #有返回值 
 Dict.clear () 
 #dict. Popitem () #随机删除     

Collection operations

#作用: de-weight, relational operations,

#定义:
Review of Knowledge points
mutable types are notHash type
Immutable types are availableHash type
#定义集合:
Collection: Can contain multiple elements, separated by commas,
The elements of a collection follow three principles:
1: Each element must be of immutable type (can behash, which can be used as a dictionary key)
2: No duplicate elements
3: Unordered
Note that the purpose of a collection is to store different values together, and to do relational operations between different sets, without having to tangle with individual values in the collection
#set把不同的元素集合在一起 (not the same) unordered, Frozenset immutable collection, which can be traversed with a for, iterator, and in to determine whether the element is in the collection
L = [' Zhang ',' Wang ',' Zhang ']
s =Set' Alex Li ')
S1 =Set (L)
Print (s)#{', ' a ', ' X ', ' l ', ' e ', ' I '}
Print (S1)#{' Wang ', ' Zhang '}
PrintType (S1))#<class ' Set ' > type represents the types of data

Li = [(),' AA ', 1]
SS =Set (LI)
Print (ss) #{(1, 2), 1, ' AA '}
Ss.add (78)#增一个元素
Ss.update ("NMK")#增三个元素
Print (ss) #{(1, 2), 1, +, ' m ', ' n ', ' k ', ' AA '}
Ss.remove (1)#删除
AA = Ss.pop ()#删除, and a clear

Print (set ("qwer") = = Set ("Qwerewq"))#true
Print (set ("Qwer") < set ("Qwer"))#false子集
A = set ([1,2,3,4,5])
b = set ([4,5,6,7,8])
AA = A.intersection (b)#交集
Print (AA) #{4, 5}
Print (A.union (b))#并集 {1, 2, 3, 4, 5, 6, 7, 8}
Print (A.difference (b))#差集 {1, 2, 3}
Print (A.symmetric_difference (b))#对称差集 {1, 2, 3, 6, 7, 8}
The following wording is equivalent to the above, more simple
A|b #并集
A&b# Intersection
A-B#差集
A^b #对称差集

#父级a是b的父级 >
A.issuperset (b)
#子集 <
A.issubset (b)                

Python Basic Data type operation