# 初学者如何学习Python？掌握这17个实用小技巧快速入门！

Python是机器学习的主流语言，没有之一。今年5月，它首次在PYPL排行榜上超越JAVA，成为全球第一大编程语言。而一个月后，Stack Overflow也分享了最新的编程语言浏览量统计数字，结果显示，Python的月活历史性地超越了Java和JavaScript，真正问鼎榜首。

“人生苦短，我选Python”。那么，你真的掌握了Python吗？下面我为大家介绍Python初学的17个学习小技巧！

1、交换变量

# 输入

a = 5

b = 10

#创建临时变量

temp = a

a = b

b = temp

print(a)

print(b)

2、if 语句在行内

print "Hello" if True else "World"

3、连接

nfc = ["Packers", "49ers"]

afc = ["Ravens", "Patriots"]

print nfc + afc

>>> ['Packers', '49ers', 'Ravens', 'Patriots']

print str(1) + " world"

>>> 1 world

print `1` + " world"

>>> 1 world

print 1, "world"

>>> 1 world

print nfc, 1

>>> ['Packers', '49ers'] 1

4、计算技巧

#向下取整

print 5.0//2

# 2的5次方

print 2**5

print .3/.1

>>> 2.9999999999999996

print .3//.1

5、数值比较

x = 2

if 3 > x > 1:

print x

if 1 0:

print x

6、两个列表同时迭代

nfc = ["Packers", "49ers"]

afc = ["Ravens", "Patriots"]

for teama, teamb in zip(nfc, afc):

print teama + " vs. " + teamb

>>> Packers vs. Ravens

>>> 49ers vs. Patriots

7、带索引的列表迭代

teams = ["Packers", "49ers", "Ravens", "Patriots"]

for index, team in enumerate(teams):

print index, team

>>> 0 Packers

>>> 1 49ers

>>> 2 Ravens

>>> 3 Patriots

8、列表推导

numbers = [1,2,3,4,5,6]

even = []

for number in numbers:

if number%2 == 0:

even.append(number)

9、用下面的代替

numbers = [1,2,3,4,5,6]

even = [number for number in numbers if number%2 == 0]

10、字典推导

teams = ["Packers", "49ers", "Ravens", "Patriots"]

print

>>> {'49ers': 1, 'Ravens': 2, 'Patriots': 3, 'Packers': 0}

11、初始化列表的值

items = [0]*3

print items

>>> [0,0,0]

12、将列表转换成字符串

teams = ["Packers", "49ers", "Ravens", "Patriots"]

print ", ".join(teams)

>>> 'Packers, 49ers, Ravens, Patriots'

13、从字典中获取元素

data = {'user': 1, 'name': 'Max', 'three': 4}

try:

except KeyError:

data = {'user': 1, 'name': 'Max', 'three': 4}

14、获取子列表

x = [1,2,3,4,5,6]

#前3个

print x[:3]

>>> [1,2,3]

#中间4个

print x[1:5]

>>> [2,3,4,5]

#最后3个

print x[-3:]

>>> [4,5,6]

#奇数项

print x[::2]

>>> [1,3,5]

#偶数项

print x[1::2]

>>> [2,4,6]

15、60个字符解决FizzBuzz

for x in range(101):print"fizz"[x%3*4::]+"buzz"[x%5*4::]or x

16、集合

from collections import Counter

print Counter("hello")

>>> Counter({'l': 2, 'h': 1, 'e': 1, 'o': 1})

17、迭代工具

from itertools import combinations

teams = ["Packers", "49ers", "Ravens", "Patriots"]

for game in combinations(teams, 2):

print game

>>> ('Packers', '49ers')

>>> ('Packers', 'Ravens')

>>> ('Packers', 'Patriots')

>>> ('49ers', 'Ravens')

>>> ('49ers', 'Patriots')

>>> ('Ravens', 'Patriots')

False = True

if False:

print "Hello"

else:

print "World"

Python是一种面向对象的解释型计算机程序的设计语言, Python具有丰富和强大的库。它常被称为胶水语言，能够把其他语言制作的各种模块很轻松地结合在一起。

Python的发展方向：数据分析、人工智能、web开发、测试、运维、web安全、游戏制作等等。

• 发表于:
• 原文链接https://kuaibao.qq.com/s/20180903A17SK900?refer=cp_1026
• 腾讯「云+社区」是腾讯内容开放平台帐号（企鹅号）传播渠道之一，根据《腾讯内容开放平台服务协议》转载发布内容。
• 如有侵权，请联系 yunjia_community@tencent.com 删除。

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