python列表-序列通用操作

序列之—通用操作

判断元素是否在序列之内

>>> names = ['tom','jerry','mike','peter','john']
>>> scores = [99,88,76.3,90.5,77]
>>> 'meki' in names
False
>>> 'mike' in names
True
>>> 88 in scores
True
>>> 101 in scores
False
>>> 101 not in scores

True

连接序列

>>> x = list(range(4))
>>> x
[0, 1, 2, 3]
>>> y = [98,99,100]
>>> x + y
[0, 1, 2, 3, 98, 99, 100]
>>> x
[0, 1, 2, 3]
>>> y
[98, 99, 100]

重复序列元素

>>> [3] * 4
[3, 3, 3, 3]

下标获取元素

>>> names = ['tom','jerry','mike','peter','john']
>>> scores = [99, 88, 76.3, 90.5, 77]
>>> names[0]
'tom'
>>> scores[1]
88
>>> names[-1]
'john'
>>> names[-2]
'peter'

访问指定索引范围

>>> cities = ['北京','上海','广州','深圳','天津']
>>> cities[0:2]
['北京', '上海']
>>> cities[0:3]
['北京', '上海', '广州']
>>> cities[-5:-3]
['北京', '上海']
>>> cities[:3]
['北京', '上海', '广州']
>>> cities[0:4]
['北京', '上海', '广州', '深圳']
>>> cities[0:-1]
['北京', '上海', '广州', '深圳']
>>> cities[1:]
['上海', '广州', '深圳', '天津']
>>> cities[:]
['北京', '上海', '广州', '深圳', '天津']

按步长访问指定索引范围

>>> cities[:]
['北京', '上海', '广州', '深圳', '天津']
>>> cities[::2]
['北京', '广州', '天津']
>>> cities[::3]
['北京', '深圳']

获取序列长度

>>> len(cities)
5

获取最大值 、获取最小值 、统计值

>>> scores = [98,88.2,97.5,60,77.3]
>>> len(scores)
5
>>> min(scores)
60
>>> max(scores)
98
>>> sum(scores)
421.0

检索某个元素第一次出现位置下标

>>> cities
['北京', '上海', '广州', '深圳', '天津']
>>> scores
[98, 88.2, 97.5, 60, 77.3]
>>> cities.index('上海')
1
>>> cities.index('广州')
2
>>> scores.index(98)
0

统计元素出现的次数

>>> cities
['北京', '上海', '广州', '深圳', '天津']
>>> scores
[98, 88.2, 97.5, 60, 77.3]
>>> cities.count('天津')
1
>>> scores.count(88.2)
1
>>> l = [1,2,3,4,2,3,3,1,2]
>>> l.count(2)
3