python字符類型的相互轉換

str---->list

str1 = "string"
list1 = list(str1)
print(list1)

str2 = "i am ybc"
list2 = str2.split()
print(list2)

str3 = "www.google.com"
list3 = str3.split(".")
print(list3)

#運行結果
['s', 't', 'r', 'i', 'n', 'g']
['i', 'am', 'ybc']
['www', 'google', 'com']

list---->str

str4 = "".join(list1)
print(str4)
str5 = " ".join(list2)
print(str5)
str6 = ".".join(list3)
print(str6)

#運行結果
string
i am ybc
www.google.com

str---->dict

內置函數eval

將字符串str當成有效的表達式來求值並返回計算結果
無法處理多維字典；字符串裏面的字符必須是單引號

user = "{'name' : 'zhangsan', 'sex' : 'male', 'age': 20}"
dict1 = eval(user)
print(dict1)

#運行結果
{'name': 'zhangsan', 'sex': 'male', 'age': 20}

json包

字符串裏面的字符必須是雙引號

import json
user = '{"name":"zhangsan","sex":"male","age":"20"}'
dict2 = json.loads(user)
print(dict2)

#運行結果
{'name': 'zhangsan', 'sex': 'male', 'age': '20'}

dict---->str

內置方法str

dict = {'name': 'zhangsan', 'sex': 'male', 'age': '20'}
str = str(dict)
print(type(str), str)

#運行結果
<class 'str'> {'name': 'zhangsan', 'sex': 'male', 'age': '20'}

json包

import json
dict = {'name': 'zhangsan', 'sex': 'male', 'age': '20'}
str = json.dumps(dict)
print(type(str), str)

#運行結果
<class 'str'> {"name": "zhangsan", "sex": "male", "age": "20"}

dict---->list

list函數取key，vlaue值

list函數默認是將字典中的key取出來，返回list

dict = {'name': 'zhangsan', 'sex': 'male', 'age': '20'}
#字典中的key轉換爲列表
list1 = list(dict.keys())
#字典中的value轉換爲列表
list2 = list(dict.values())
print(list1, list2)

#運行結果
['name', 'sex', 'age'] ['zhangsan', 'male', '20']

for循環

dict = {'name': 'zhangsan', 'sex': 'male', 'age': '20'}
list_key = []
list_value = []
for key, value in dict.items():
    list_key.append(key)
    list_value.append(value)
print(list_key, list_value)

#運行結果
['name', 'sex', 'age'] ['zhangsan', 'male', '20']

list---->dict

list = ['zhangsan', '18']
dict = {}
for i in range(len(list)):
    dict[i] = list[i]
print(dict)

#運行結果
{0: 'zhangsan', 1: '18'}

str---->tuple

python的元組與列表類似，但元組的元素不能修改

直接轉換

str轉化爲tuple，直接進行轉換

str = "zhangsan 18"
tuple = tuple(str)
print(tuple)

#運行結果
('z', 'h', 'a', 'n', 'g', 's', 'a', 'n', ' ', '1', '8')

藉助list

str = "zhangsan 18"
tuple = tuple(str.split())
print(tuple)

#運行結果
('zhangsan', '18')

tuple---->str

tuple轉換爲str需要藉助join()函數來實現

tuple = ('z', 'h', 'a', 'n', 'g', 's', 'a', 'n', ' ', '1', '8')
str = "".join(tuple)
print(str)

#運行結果
zhangsan 18

list---->tuple

list = ['zhangsan', '18']
tuple = tuple(list)
print(tuple)

#運行結果
('zhangsan', '18')