Python slice

原创转载请注明出处：http://agilestyle.iteye.com/blog/2328911

L = ['GuanYu', 'ZhangFei', 'ZhaoYun', 'MaChao', 'HuangZhong']
 
# get the first 3 elements
# ['GuanYu', 'ZhangFei', 'ZhaoYun']
print(L[0:3])
# ['GuanYu', 'ZhangFei', 'ZhaoYun']
print(L[:3])
 
# get the last 2 elements
# ['MaChao', 'HuangZhong']
print(L[-2:])
# ['MaChao']
print(L[-2:-1])

Console Output

Python支持L[-1]取倒数第一个元素, 记住倒数第一个元素的索引是-1

L = list(range(100))
# get the first 10 elements
print(L[:10])
# get the last 10 elements
print(L[-10:])
# get 11 - 20 elements
print(L[10:20])
# 前10个数，每2个取一个
# [0, 2, 4, 6, 8]
print(L[:10:2])
# 所有数，每5个取一个
# [0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95]
print(L[::5])
# 只写[:]就可以原样复制一个list
print(L[:])

Console Output

 
tuple也是一种list，唯一区别是tuple不可变

t = (0, 1, 2, 3, 4, 5)[:3]
# (0, 1, 2)
print(t)

字符串'xxx'也可以看成是一种list，每个元素就是一个字符

str1 = 'ABCDEFG'[:3]
# ABC
print(str1)
# ACEG
str2 = 'ABCDEFG'[::2]
print(str2)

Console Output