記錄幾個python語法的小技巧。

1. 變換變量

x = 5
y = 6
x, y = y, x
print  x,y

2. 行內(nèi)if語句

print 'Python' if True else 'Objective-C'

3.連接

l1 = ['python','objective-c']
l2 = ['swift']
l3 = l1 + l2
print l3

4.向下取整

print 5.0//2
print 2**5

5.浮點數(shù)的除法

print .3/.1
print .3//.1

6.數(shù)值比較

x = 2
if 3 > x < 1:
    print x
if 1 < x > 0:
    print x

7.兩個列表同時迭代

l1 = ['python','objective-c']
l2 = ['swift','javascript']
#zip把兩個列表組合成一個列表,但是新的列表里面每一個值都是一個tuple
for item1,item2 in zip(l1,l2):
    print item1,item2

8.帶索引的迭代

l1 = ['python','objective-c','swift','javascript']
for index,language in enumerate(l1):
print language + ' index is ' + str(index)

9.列表推導(dǎo)

nums = [x for x in range(11)]
    print nums
nums2 = [x for x in nums if x%2 == 0]
    print nums2

10.索引推導(dǎo)

dict = {'name':'shuige','age':'20'}
    print {key:value for value,key in enumerate(dict)}

11.初始化列表

items = [0]*3
    print items

12.列表轉(zhuǎn)換成字符串

l1 = ['python','objective-c','swift','javascript']
    print ','.join(l1)

13.字典取元素

dict = {'name':'shuige','age':'20'}
#如果有值,打印,沒有的話,會打印True
name = dict.get('name',True)
    print name

14.切片

x = [x for x in range(11)]
print x[:3]
print x[1::2] #從索引1開始每隔兩個
print x[1::3]