python函数记不住怎么办_初学python 容易忘记的15条小技巧

初学python 掌握了基础的语法知识后 往往容易忘记一些经常使用的方法 又要花费不少时间去查找使用 于是我列出了下列15条小技巧 可能对于部分人来说过于基础 但是对于我们这些刚刚入门的人来说 还是有不少用处的

1. 交换值

x, y = 1, 2

print(x, y)

x, y = y, x

print(x, y)

2. 字符串列表合并为一个字符串

sentence_list = ["my", "name", "is", "George"]

sentence_string = " ".join(sentence_list)

print(sentence_string)

3. 将字符串拆分为子字符串列表

sentence_string = "my name is George"

sentence_string.split()

print(sentence_string)

4. 通过数字填充初始化列表

[0]*1000 # List of 1000 zeros

[8.2]*1000 # List of 1000 8.2's

5. 字典合并

x = {'a': 1, 'b': 2}

y = {'b': 3, 'c': 4}

z = {**x, **y}

6. 反转字符串

name = "George"

name[::-1]

7. 从函数返回多个值

def get_a_string():

a = "George"

b = "is"

c = "cool"

return a, b, c

sentence = get_a_string()

(a, b, c) = sentence

8. 列表解析式

a = [1, 2, 3]

b = [num*2 for num in a] # Create a new list by multiplying each element in a by 2

9. 遍历字典

m = {'a': 1, 'b': 2, 'c': 3, 'd': 4}

for key, value in m.items():

print('{0}: {1}'.format(key, value))

10. 同时遍历列表的索引和值

m = ['a', 'b', 'c', 'd']

for index, value in enumerate(m):

print('{0}: {1}'.format(index, value))

11. 初始化空容器

a_list = list()

a_dict = dict()

a_map = map()

a_set = set()

12. 删除字符串两端的无用字符

name = " George "

name_2 = "George///"

name.strip() # prints "George"

name_2.strip("/") # prints "George"

13. 列表中出现最多的元素

test = [1, 2, 3, 4, 2, 2, 3, 1, 4, 4, 4]

print(max(set(test), key = test.count))

14. 检查对象的内存使用情况

import sys

x = 1

print(sys.getsizeof(x))

15. 将 dict 转换为 XML

from xml.etree.ElementTree import Element

def dict_to_xml(tag, d):

'''

Turn a simple dict of key/value pairs into XML

'''

elem = Element(tag)

for key, val in d.items():

child = Element(key)

child.text = str(val)

elem.append(child)

return elem