优雅你的python代码

作为程序员，要从平凡写出优雅。

本文每两断代码为一个模块去理解：

1. 关于python中多变量赋值：

a = 0 
b = 1
c = 2

优雅起来：
使用元祖语法

a, b, c = 0, 1, 2

2. 序列解包：

 colors = ['red', 'black', 'yellew', 100]
 red = colors[0]
 black = colors[1]
 yellew = colors[2]
 num = colors[3]
 

优雅起来：
序列自动解包

 red, black, yellew, num = ['red', 'black', 'yellew', 100]

3. 减少中介变量，少嵌套

name = 'Hello, World!!'
a = name.replace.(',','')
b = a.replace.('!!','')
print(b)

name = 'Hello, World!!'
b = name.replace.(',','').replace.('!!','')
print(b)

4. 三目运算 if … else…

 a = 100
 if a>=0:
 	b = a
 else:
 	b = -a
 print(b)

优雅起来：

a = 100
b= a if a>=0 else -100

5. 区间判断

score = 100
if score >= 50 and score < 60
	print('及格')

优雅起来
链式判断

score = 100
if 50 <= score < 60:
	print('及格')

6. 判断是否为多个值之一

if num in == 1 or num == 'd' or num == '2':
	print(num)

使用关键字in

if num in (1,'d','2'):
	print(num)

7. 判断是否为空列表，空字典，空字符串

i,y,z = [1,2,3], {
     }, ''
if len(i)>0:
	print('...')
if len(y)>0:
	print('...')
if len(z)>0:
	print('...')

优雅起来：
隐含类型转换直接判断

i,y,z = [1,2,3], {
     }, ''
if i:
	pass
if y:
	pass
if z:
	pass

8. 诸多条件是否至少有一个成立

book, card, num = 10, 20, 30

if book < 30 or card <30 or num < 30:
	printy('...')

优雅起来
使用any函数

book, card, num = 10, 20, 30
if any([ book<30, card<30, num <30 ]):
	pass

9. 诸多条件是否全部成立

book, card, num = 10, 20, 25

if book < 30 or card <30 or num < 30:
	printy('...')

优雅起来
使用any函数

book, card, num = 10, 20, 30
if all([ book<30, card<30, num <30 ]):
	pass

9. 推导式

## 计算 a 中全部数值并求和
a = [1,2,3,'dadada',4,5]
list = []
for i in a:
	if isinstance(i,(int,float)):
		list.append(i)
sum(list)

优雅起来
推导式

a = [1,2,3,'dadada',4,5]
sum([i for i in a if type(i) in [int,float]])

10. 同时遍历序列的元素和元素下标

 colors = ['red', 'black', 'yellew', 100]
 for i in range(len(colors )):
 	print(i:':',colors[i] )

优雅起来
使用enumerate函数生成下标和元素对

 colors = ['red', 'black', 'yellew', 100]
 for i,s in enumerate(colors):
 	print(i,':',s)

11. 显示循环进度

这里说每个一秒打印一行结果

import time
for i in range(100):
	times.sleep(0.1)
	print(i)

import time
for i in range(100):
	times.sleep(0.1)
	print(i, end='\r')

def process_bar(num, total):
	rate = float(num)/total
	ratenum = int(100*rate)
	r = '\r[{} {}]{}%'.format('*'*ratenum, ' '*(100-ratenum), ratenum)
	sys.stdout.write(r)
	sys.stdout.flush()

i,n = 0,100
for i in range(n):
	time.sleep(0.1)
	process_bar(i+1,n)