1.随机选择
python中生成随机数使用random模块。
1.从序列中随机挑选元素，使用random.choice()
>>> import random
>>> values = [1, 2, 3, 4, 5, 6]
>>> random.choice(values)
3
>>> random.choice(values)
3
>>> random.choice(values)
1
>>> random.choice(values)
1
>>> random.choice(values)
4
2.取出指定个数的元素，使用random.sample()
>>> random.sample(values, 2)
[1, 4]
>>> random.sample(values, 2)
[3, 5]
>>> random.sample(values, 3)
[5, 3, 2]
>>> random.sample(values, 3)
[1, 3, 2]
3.打乱序列的顺序，可以用来洗牌，使用random.shuffle()
>>> random.shuffle(values)
>>> values
[2, 4, 5, 3, 6, 1]
>>> random.shuffle(values)
>>> values
[2, 6, 5, 4, 3, 1]
4.生成随机整数，使用random.randint()
>>> random.randint(1, 10)
3
>>> random.randint(1, 10)
10
>>> random.randint(1, 10)
5
5.生成 0 到 1 之间的浮点数，使用random.random()
>>> random.random()
0.31720220264500265
>>> random.random()
0.8230452349376671
>>> random.random()
0.09307172325744872
6.生成随机比特位的整数，使用random.getrandbits()
>>> random.getrandbits(200)
859899606181938256764615251875627706548045135119258688489931
>>> random.getrandbits(200)
582401031226834278134883678914218487507678688169321631685078
2.时间的转换
1.python中使用datetime模块来转换时间。
>>> from datetime import timedelta
>>> a = timedelta(days = 2, hours = 6)
>>> b = timedelta(hours = 4.5)
>>> c = a + b
>>> c.days
2
>>> c.seconds
37800
>>> c.seconds / 3600
10.5
>>> c.total_seconds() / 3600
58.5
表示特定的日期和时间。
>>> from datetime import datetime
>>> a = datetime(2017, 9, 8)
>>> print(a + timedelta(days=2))
2017-09-10 00:00:00
>>> b = datetime(2017, 9, 22)
>>> d = b - a
>>> d.days
14
>>> now = datetime.today()
>>> print(now)
2017-09-08 20:09:56.904169
>>> print(now + timedelta(minutes=10))
2017-09-08 20:19:56.904169
2.使用dateutil模块，可以处理不同月份中的天数。datetime不能处理月份。
>>> from dateutil.relativedelta import relativedelta
>>> a = datetime(2017, 9, 8)
>>> a + relativedelta(months=1)
datetime.datetime(2017, 10, 8, 0, 0)
>>> a + relativedelta(months=4)
datetime.datetime(2018, 1, 8, 0, 0)
>>> b = datetime(2017, 11, 11)
>>> d = b - a
>>> d
datetime.timedelta(64)
>>> d = relativedelta(b, a)
>>> d
relativedelta(months=+2, days=+3)
>>> d.months
2
>>> d.days
3
3.把字符串转换为时间，使用datetime.strptime()，把时间转化为字符串使用datetime.strftime()
>>> from datetime import datetime
>>> text = '2017-9-8'
>>> y = datetime.strptime(text, '%Y-%m-%d')
>>> z = datetime.now()
>>> diff = z - y
>>> diff
datetime.timedelta(0, 73494, 826144)
>>> y
datetime.datetime(2017, 9, 8, 0, 0)
>>> z
datetime.datetime(2017, 9, 8, 20, 24, 54, 826144)
>>> nice_z = datetime.strftime(z, '%A %B %d %Y')
>>> nice_z
'Friday September 08 2017'