数据挖掘：Pandas时间模块管理！

时间  2021-02-18
标签 dom 函数 code orm 对象 索引 string pandas class 栏目 HTML 繁體版
原文   原文链接

datetime

import numpy as np
import pandas as pd
import datetimedom

# datetime.date
​
t = datetime.date.today()  # datetime 模块 date 类 today() 类方法
print(t, type(t))
print("")
​
t_str = str(t)
print(t, type(t_str))函数

2019-05-26 <class 'datetime.date'>
​
2019-05-26 <class 'str'>code

# datetime.datetime
​
now = datetime.datetime.now()
print(now, type(now))orm

2019-05-26 16:18:17.612845 <class 'datetime.datetime'>对象

# datetime.timedelta 时间差
​
t1 = datetime.datetime(2017,10,1)
print(t1)
print("")
​
tx = datetime.timedelta(100)  # timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)
print(tx)
print("")
​
t2 = t1 + tx
print(t2)索引

2017-10-01 00:00:00
​
100 days, 0:00:00
​
2018-01-09 00:00:00string

pd.Timestamp 跟datetime做用相同 只不过Timestamp是pd模块里的

import numpy as np
import pandas as pd
import datetimepandas

t = datetime.datetime.today()
print(t)
print("")
​
ts1 = pd.Timestamp(t)
print(ts1)
print("")
​
ts2 = pd.Timestamp("20171021")
print(ts2)io

2020-06-01 14:28:08.656056
​
2020-06-01 14:28:08.656056
​
2017-10-21 00:00:00class

pd.to_datetime 多个时间数据转换成时间戳索引

time_list = ["20171019", "20181020", "20191021"]
​
t = pd.to_datetime(time_list)
print(t, type(t))

DatetimeIndex(['2017-10-19', '2018-10-20', '2019-10-21'], dtype='datetime64[ns]', freq=None) <class 'pandas.core.indexes.datetimes.DatetimeIndex'>

若是时间序列里包含非时间的数据 ignore(忽略异常 但不会转换成时间戳索引) coerce(把异常值改成NaT)

time_list1 = ["20171019", "20181020", "bbbb", "20191021"]
​
t1= pd.to_datetime(time_list1, errors="ignore")
print(t1, type(t1))
print("")
​
t2 = pd.to_datetime(time_list1, errors="coerce")
print(t2)

Index(['20171019', '20181020', 'bbbb', '20191021'], dtype='object') <class 'pandas.core.indexes.base.Index'>
​
DatetimeIndex(['2017-10-19', '2018-10-20', 'NaT', '2019-10-21'], dtype='datetime64[ns]', freq=None)

pd.DatetimeIndex() 直接生成时间戳序列

rng = pd.DatetimeIndex(["20160910", "11/06/2017", "20180821", "26/05/2019"])
print(rng)
print(type(rng))
print("")
​
print(rng[0], type(rng[0]))

DatetimeIndex(['2016-09-10', '2017-11-06', '2018-08-21', '2019-05-26'], dtype='datetime64[ns]', freq=None)
<class 'pandas.core.indexes.datetimes.DatetimeIndex'>
​
2016-09-10 00:00:00 <class 'pandas._libs.tslibs.timestamps.Timestamp'>

st = pd.Series(np.random.rand(4), index=rng) # 把时间戳索引当成index
print(st)

2016-09-10   0.835586
2017-11-06   0.223044
2018-08-21   0.950717
2019-05-26   0.013370
dtype: float64

pd.date_range() 生成日期范围

"""
pd.date_range(start=None, end=None, periods=None, freq=None, tz=None, normalize=False, name=None ,closed=None, **kwargs)
​
该函数主要用于生成一个固定频率的时间索引，在调用构造方法时，必须指定start、end、periods中的两个参数值，不然报错。
​
start: 开始日期
​
end: 结束日期
​
periods：固定时期，取值为整数或None
​
freq：日期偏移量，取值为string或DateOffset，默认为'D'
​
normalize：若参数为True表示将start、end参数值正则化到午夜时间戳 0:00:00 默认为False
​
name：生成时间索引对象的名称，取值为string或None
​
closed：能够理解成在closed=None状况下返回的结果中，若closed=‘left’表示在返回的结果基础上，再取左开右闭的结果，若closed='right'表示在返回的结果基础上，再取左闭右开的结果
​
"""

"\npd.date_range(start=None, end=None, periods=None, freq=None, tz=None, normalize=False, name=None ,closed=None, **kwargs)\n\n该函数主要用于生成一个固定频率的时间索引，在调用构造方法时，必须指定start、end、periods中的两个参数值，不然报错。\n\nstart: 开始日期\n\nend: 结束日期\n\nperiods：固定时期，取值为整数或None\n\nfreq：日期偏移量，取值为string或DateOffset，默认为'D'\n\nnormalize：若参数为True表示将start、end参数值正则化到午夜时间戳 0:00:00 默认为False\n\nname：生成时间索引对象的名称，取值为string或None\n\nclosed：能够理解成在closed=None状况下返回的结果中，若closed=‘left’表示在返回的结果基础上，再取左开右闭的结果，若closed='right'表示在返回的结果基础上，再取左闭右开的结果\n\n"

start end

t_index1 = pd.date_range(start="20181018", end="20191021", name="t_index1")
print(t_index1)

DatetimeIndex(['2018-10-18', '2018-10-19', '2018-10-20', '2018-10-21',
'2018-10-22', '2018-10-23', '2018-10-24', '2018-10-25',
'2018-10-26', '2018-10-27',
...
'2019-10-12', '2019-10-13', '2019-10-14', '2019-10-15',
'2019-10-16', '2019-10-17', '2019-10-18', '2019-10-19',
'2019-10-20', '2019-10-21'],
dtype='datetime64[ns]', name='t_index1', length=369, freq='D')

periods

t_index2 = pd.date_range(start="20181018", periods=10, name="t_index2")
print(t_index2)

DatetimeIndex(['2018-10-18', '2018-10-19', '2018-10-20', '2018-10-21',
'2018-10-22', '2018-10-23', '2018-10-24', '2018-10-25',
'2018-10-26', '2018-10-27'],
dtype='datetime64[ns]', name='t_index2', freq='D')

t_index3 = pd.date_range(end="20181018", periods=10, name="t_index3")
print(t_index3)

DatetimeIndex(['2018-10-09', '2018-10-10', '2018-10-11', '2018-10-12',
'2018-10-13', '2018-10-14', '2018-10-15', '2018-10-16',
'2018-10-17', '2018-10-18'],
dtype='datetime64[ns]', name='t_index3', freq='D')

name normalize

t_index4 = pd.date_range(start="11/09/2019 16:30", periods=10, name="t_index4")
print(t_index4)
print("\n")
​
t_index4 = pd.date_range(start="11/09/2019 16:30", periods=10, name="t_index4", normalize=True)
print(t_index4)

DatetimeIndex(['2019-11-09 16:30:00', '2019-11-10 16:30:00',
'2019-11-11 16:30:00', '2019-11-12 16:30:00',
'2019-11-13 16:30:00', '2019-11-14 16:30:00',
'2019-11-15 16:30:00', '2019-11-16 16:30:00',
'2019-11-17 16:30:00', '2019-11-18 16:30:00'],
dtype='datetime64[ns]', name='t_index4', freq='D')

DatetimeIndex(['2019-11-09', '2019-11-10', '2019-11-11', '2019-11-12',
'2019-11-13', '2019-11-14', '2019-11-15', '2019-11-16',
'2019-11-17', '2019-11-18'],
dtype='datetime64[ns]', name='t_index4', freq='D')

closed

t_index5 = pd.date_range(start="20190910", end="20190918", name="t_index5")
print(t_index5)
print("\n")
​
t_index5 = pd.date_range(start="20190910", end="20190918", name="t_index5", closed="left") # 左闭右开
print(t_index5)
print("\n")
​
t_index5 = pd.date_range(start="20190910", end="20190918", name="t_index5", closed="right") # 左开右闭
print(t_index5)
print("\n")

DatetimeIndex(['2019-09-10', '2019-09-11', '2019-09-12', '2019-09-13',
'2019-09-14', '2019-09-15', '2019-09-16', '2019-09-17',
'2019-09-18'],
dtype='datetime64[ns]', name='t_index5', freq='D')

DatetimeIndex(['2019-09-10', '2019-09-11', '2019-09-12', '2019-09-13',
'2019-09-14', '2019-09-15', '2019-09-16', '2019-09-17'],
dtype='datetime64[ns]', name='t_index5', freq='D')

DatetimeIndex(['2019-09-11', '2019-09-12', '2019-09-13', '2019-09-14',
'2019-09-15', '2019-09-16', '2019-09-17', '2019-09-18'],
dtype='datetime64[ns]', name='t_index5', freq='D')

pd.bdate_range() 默认频率为工做日

t_index6 = pd.bdate_range(start="20191001", end="20191007", name="t_index6")
print(t_index6)

DatetimeIndex(['2019-10-01', '2019-10-02', '2019-10-03', '2019-10-04',
'2019-10-07'],
dtype='datetime64[ns]', name='t_index6', freq='B')

pd.date_range 转换成list 元素为时间戳Timestamp

t_index7_list= pd.date_range(start="20191001", end="20191007", name="t_index7_list")
print(t_index7_list)
print("\n")
​
t_index7_list= list(pd.date_range(start="20191001", end="20191007", name="t_index7_list"))
print(t_index7_list)

DatetimeIndex(['2019-10-01', '2019-10-02', '2019-10-03', '2019-10-04',
'2019-10-05', '2019-10-06', '2019-10-07'],
dtype='datetime64[ns]', name='t_index7_list', freq='D')

[Timestamp('2019-10-01 00:00:00', freq='D'), Timestamp('2019-10-02 00:00:00', freq='D'), Timestamp('2019-10-03 00:00:00', freq='D'), Timestamp('2019-10-04 00:00:00', freq='D'), Timestamp('2019-10-05 00:00:00', freq='D'), Timestamp('2019-10-06 00:00:00', freq='D'), Timestamp('2019-10-07 00:00:00', freq='D')]

fred 日期偏移量

# 默认freq = 'D' 每日
​
pd.date_range("10/1/2019", "2019/10/7")

DatetimeIndex(['2019-10-01', '2019-10-02', '2019-10-03', '2019-10-04',
'2019-10-05', '2019-10-06', '2019-10-07'],
dtype='datetime64[ns]', freq='D')

# 'B' 每工做日
​
pd.date_range("10/01/2019", "10/07/2019", freq = "B")

DatetimeIndex(['2019-10-01', '2019-10-02', '2019-10-03', '2019-10-04',
'2019-10-07'],
dtype='datetime64[ns]', freq='B')

# H 每小时
​
pd.date_range("10/01/2019 12:00:00", "10/02/2019 12:00:00", freq = "H")

DatetimeIndex(['2019-10-01 12:00:00', '2019-10-01 13:00:00',
'2019-10-01 14:00:00', '2019-10-01 15:00:00',
'2019-10-01 16:00:00', '2019-10-01 17:00:00',
'2019-10-01 18:00:00', '2019-10-01 19:00:00',
'2019-10-01 20:00:00', '2019-10-01 21:00:00',
'2019-10-01 22:00:00', '2019-10-01 23:00:00',
'2019-10-02 00:00:00', '2019-10-02 01:00:00',
'2019-10-02 02:00:00', '2019-10-02 03:00:00',
'2019-10-02 04:00:00', '2019-10-02 05:00:00',
'2019-10-02 06:00:00', '2019-10-02 07:00:00',
'2019-10-02 08:00:00', '2019-10-02 09:00:00',
'2019-10-02 10:00:00', '2019-10-02 11:00:00',
'2019-10-02 12:00:00'],
dtype='datetime64[ns]', freq='H')

# T/MIN 每分
​
pd.date_range("10/01/2019 12:10:00" , "10/01/2019 12:30:00", freq = "T")

DatetimeIndex(['2019-10-01 12:10:00', '2019-10-01 12:11:00',
'2019-10-01 12:12:00', '2019-10-01 12:13:00',
'2019-10-01 12:14:00', '2019-10-01 12:15:00',
'2019-10-01 12:16:00', '2019-10-01 12:17:00',
'2019-10-01 12:18:00', '2019-10-01 12:19:00',
'2019-10-01 12:20:00', '2019-10-01 12:21:00',
'2019-10-01 12:22:00', '2019-10-01 12:23:00',
'2019-10-01 12:24:00', '2019-10-01 12:25:00',
'2019-10-01 12:26:00', '2019-10-01 12:27:00',
'2019-10-01 12:28:00', '2019-10-01 12:29:00',
'2019-10-01 12:30:00'],
dtype='datetime64[ns]', freq='T')

# S 每秒
​
pd.date_range("10/01/2019", "10/01/2019 00:00:30", freq = "S")

DatetimeIndex(['2019-10-01 00:00:00', '2019-10-01 00:00:01',
'2019-10-01 00:00:02', '2019-10-01 00:00:03',
'2019-10-01 00:00:04', '2019-10-01 00:00:05',
'2019-10-01 00:00:06', '2019-10-01 00:00:07',
'2019-10-01 00:00:08', '2019-10-01 00:00:09',
'2019-10-01 00:00:10', '2019-10-01 00:00:11',
'2019-10-01 00:00:12', '2019-10-01 00:00:13',
'2019-10-01 00:00:14', '2019-10-01 00:00:15',
'2019-10-01 00:00:16', '2019-10-01 00:00:17',
'2019-10-01 00:00:18', '2019-10-01 00:00:19',
'2019-10-01 00:00:20', '2019-10-01 00:00:21',
'2019-10-01 00:00:22', '2019-10-01 00:00:23',
'2019-10-01 00:00:24', '2019-10-01 00:00:25',
'2019-10-01 00:00:26', '2019-10-01 00:00:27',
'2019-10-01 00:00:28', '2019-10-01 00:00:29',
'2019-10-01 00:00:30'],
dtype='datetime64[ns]', freq='S')

# L 每毫秒 (千分之一秒)
​
pd.date_range("10/01/2019", "10/01/2019 00:00:30", freq = "L")

DatetimeIndex([       '2019-10-01 00:00:00', '2019-10-01 00:00:00.001000',
'2019-10-01 00:00:00.002000', '2019-10-01 00:00:00.003000',
'2019-10-01 00:00:00.004000', '2019-10-01 00:00:00.005000',
'2019-10-01 00:00:00.006000', '2019-10-01 00:00:00.007000',
'2019-10-01 00:00:00.008000', '2019-10-01 00:00:00.009000',
...
'2019-10-01 00:00:29.991000', '2019-10-01 00:00:29.992000',
'2019-10-01 00:00:29.993000', '2019-10-01 00:00:29.994000',
'2019-10-01 00:00:29.995000', '2019-10-01 00:00:29.996000',
'2019-10-01 00:00:29.997000', '2019-10-01 00:00:29.998000',
'2019-10-01 00:00:29.999000',       '2019-10-01 00:00:30'],
dtype='datetime64[ns]', length=30001, freq='L')

# U 每微秒 (百万分之一秒)
​
pd.date_range("10/01/2019", "10/01/2019 00:00:30", freq = "U") # U 每微秒 (百万分之一秒)

DatetimeIndex([ '2019-10-01 00:00:00', '2019-10-01 00:00:00.000001',

'2019-10-01 00:00:00.000002', '2019-10-01 00:00:00.000003',
           '2019-10-01 00:00:00.000004', '2019-10-01 00:00:00.000005',
           '2019-10-01 00:00:00.000006', '2019-10-01 00:00:00.000007',
           '2019-10-01 00:00:00.000008', '2019-10-01 00:00:00.000009',
           ...
           '2019-10-01 00:00:29.999991', '2019-10-01 00:00:29.999992',
           '2019-10-01 00:00:29.999993', '2019-10-01 00:00:29.999994',
           '2019-10-01 00:00:29.999995', '2019-10-01 00:00:29.999996',
           '2019-10-01 00:00:29.999997', '2019-10-01 00:00:29.999998',
           '2019-10-01 00:00:29.999999',        '2019-10-01 00:00:30'\],
          dtype='datetime64\[ns\]', length=30000001, freq='U')

星期几缩写 -- MON/TUE/WED/THU/FRI/SAT/SUN

# "W-MON"指定从星期一开始算起 间隔是每周
​
pd.date_range("2019/10/1", "2019/11/1", freq = "W-MON")

DatetimeIndex(['2019-10-07', '2019-10-14', '2019-10-21', '2019-10-28'], dtype='datetime64[ns]', freq='W-MON')

# "WOM-2MON" 指定每个月从2第个星期一开始算起 间隔是月
​
pd.date_range("2019/10/1", "2020/10/1", freq = "WOM-2MON")

DatetimeIndex(['2019-10-14', '2019-11-11', '2019-12-09', '2020-01-13',
'2020-02-10', '2020-03-09', '2020-04-13', '2020-05-11',
'2020-06-08', '2020-07-13', '2020-08-10', '2020-09-14'],
dtype='datetime64[ns]', freq='WOM-2MON')

# M -- 每个月最后一个日历日
​
pd.date_range("2019", "2020", freq = "M")

DatetimeIndex(['2019-01-31', '2019-02-28', '2019-03-31', '2019-04-30',
'2019-05-31', '2019-06-30', '2019-07-31', '2019-08-31',
'2019-09-30', '2019-10-31', '2019-11-30', '2019-12-31'],
dtype='datetime64[ns]', freq='M')

月份

"""
一月     Jan.     January
​
二月     Feb.     February
​
三月     Mar.     March
​
四月     Apr.     April
​
五月     May.     May
​
六月     Jun.     June
​
七月     Jul.     July
​
八月     Aug.     August
​
九月     Sept.   September
​
十月     Oct.     October
​
十一月   Nov.     November
​
十二月   Dec.     December
"""

# Q 每一个季度末最后一月的最后一个日历日
​
print(pd.date_range("2019", "2020", freq="Q-JAN"))
​
print(pd.date_range("2019", "2020", freq="Q-FEB"))
​
print(pd.date_range("2019", "2020", freq="Q-MAR"))
print("")
​
# 因此Q-月只有三种状况 1-4-7-10, 2-5-8-11, 3-6-9-12
print(pd.date_range("2019", "2020", freq="Q-APR"))

DatetimeIndex(['2019-01-31', '2019-04-30', '2019-07-31', '2019-10-31'], dtype='datetime64[ns]', freq='Q-JAN')
DatetimeIndex(['2019-02-28', '2019-05-31', '2019-08-31', '2019-11-30'], dtype='datetime64[ns]', freq='Q-FEB')
DatetimeIndex(['2019-03-31', '2019-06-30', '2019-09-30', '2019-12-31'], dtype='datetime64[ns]', freq='Q-MAR')
​
DatetimeIndex(['2019-01-31', '2019-04-30', '2019-07-31', '2019-10-31'], dtype='datetime64[ns]', freq='Q-APR')

# A -- 每一年指定月份的最后一个日历日

print(pd.date_range("2019", "2021", freq="A-JAN"))
print(pd.date_range("2019", "2021", freq="A-FEB"))
print(pd.date_range("2019", "2021", freq="A-DEC"))

DatetimeIndex(['2019-01-31', '2020-01-31'], dtype='datetime64[ns]', freq='A-JAN')
DatetimeIndex(['2019-02-28', '2020-02-29'], dtype='datetime64[ns]', freq='A-FEB')
DatetimeIndex(['2019-12-31', '2020-12-31'], dtype='datetime64[ns]', freq='A-DEC')

# BM - 每个月最后一个工做日
​
print(pd.date_range("2019", "2020", freq="BM"))

DatetimeIndex(['2019-01-31', '2019-02-28', '2019-03-29', '2019-04-30',
'2019-05-31', '2019-06-28', '2019-07-31', '2019-08-30',
'2019-09-30', '2019-10-31', '2019-11-29', '2019-12-31'],
dtype='datetime64[ns]', freq='BM')

# BQ - 每一个季度末最后一月的最后一个工做日
​
print(pd.date_range("2019", "2021", freq="BQ-JAN"))
print("")
print(pd.date_range("2019", "2021", freq="BQ-FEB"))
print("")
print(pd.date_range("2019", "2021", freq="BQ-MAR"))
print("")
print(pd.date_range("2019", "2021", freq="BQ-APR"))

DatetimeIndex(['2019-01-31', '2019-04-30', '2019-07-31', '2019-10-31',
'2020-01-31', '2020-04-30', '2020-07-31', '2020-10-30'],
dtype='datetime64[ns]', freq='BQ-JAN')
​
DatetimeIndex(['2019-02-28', '2019-05-31', '2019-08-30', '2019-11-29',
'2020-02-28', '2020-05-29', '2020-08-31', '2020-11-30'],
dtype='datetime64[ns]', freq='BQ-FEB')
​
DatetimeIndex(['2019-03-29', '2019-06-28', '2019-09-30', '2019-12-31',
'2020-03-31', '2020-06-30', '2020-09-30', '2020-12-31'],
dtype='datetime64[ns]', freq='BQ-MAR')
​
DatetimeIndex(['2019-01-31', '2019-04-30', '2019-07-31', '2019-10-31',
'2020-01-31', '2020-04-30', '2020-07-31', '2020-10-30'],
dtype='datetime64[ns]', freq='BQ-APR')

# BA -- 每一年指定月份的最后一个工做日
​
print(pd.date_range("2019", "2021", freq="BA-JAN"))
print(pd.date_range("2019", "2023", freq="BA-FEB"))
print(pd.date_range("2019", "2021", freq="BA-MAR"))

DatetimeIndex(['2019-01-31', '2020-01-31'], dtype='datetime64[ns]', freq='BA-JAN')
DatetimeIndex(['2019-02-28', '2020-02-28', '2021-02-26', '2022-02-28'], dtype='datetime64[ns]', freq='BA-FEB')
DatetimeIndex(['2019-03-29', '2020-03-31'], dtype='datetime64[ns]', freq='BA-MAR')

# MS -- 每个月第一个日历日
​
pd.date_range("2019", "2020", freq="MS")

DatetimeIndex(['2019-01-01', '2019-02-01', '2019-03-01', '2019-04-01',
'2019-05-01', '2019-06-01', '2019-07-01', '2019-08-01',
'2019-09-01', '2019-10-01', '2019-11-01', '2019-12-01',
'2020-01-01'],
dtype='datetime64[ns]', freq='MS')

# QS - 每一个季度末最后一月的第一个日历日
​
print(pd.date_range("2019", "2020", freq="QS-JAN"))
print("")
print(pd.date_range("2019", "2020", freq="QS-FEB"))
print("")
print(pd.date_range("2019", "2020", freq="QS-MAR"))
print("")
print(pd.date_range("2019", "2020", freq="QS-APR"))

DatetimeIndex(['2019-01-01', '2019-04-01', '2019-07-01', '2019-10-01',
'2020-01-01'],
dtype='datetime64[ns]', freq='QS-JAN')
​
DatetimeIndex(['2019-02-01', '2019-05-01', '2019-08-01', '2019-11-01'], dtype='datetime64[ns]', freq='QS-FEB')
​
DatetimeIndex(['2019-03-01', '2019-06-01', '2019-09-01', '2019-12-01'], dtype='datetime64[ns]', freq='QS-MAR')
​
DatetimeIndex(['2019-01-01', '2019-04-01', '2019-07-01', '2019-10-01',
'2020-01-01'],
dtype='datetime64[ns]', freq='QS-APR')

# AS -- 每一年指定月份的第一个日历日
​
print(pd.date_range("2019", "2021", freq="AS-JAN"))
print(pd.date_range("2019", "2021", freq="AS-FEB"))
print(pd.date_range("2019", "2021", freq="AS-DEC"))

DatetimeIndex(['2019-01-01', '2020-01-01', '2021-01-01'], dtype='datetime64[ns]', freq='AS-JAN')
DatetimeIndex(['2019-02-01', '2020-02-01'], dtype='datetime64[ns]', freq='AS-FEB')
DatetimeIndex(['2019-12-01', '2020-12-01'], dtype='datetime64[ns]', freq='AS-DEC')

# BMS -- 每个月第一个工做日
​
print(pd.date_range("2019", "2021", freq="BMS"))

DatetimeIndex(['2019-01-01', '2019-02-01', '2019-03-01', '2019-04-01',
'2019-05-01', '2019-06-03', '2019-07-01', '2019-08-01',
'2019-09-02', '2019-10-01', '2019-11-01', '2019-12-02',
'2020-01-01', '2020-02-03', '2020-03-02', '2020-04-01',
'2020-05-01', '2020-06-01', '2020-07-01', '2020-08-03',
'2020-09-01', '2020-10-01', '2020-11-02', '2020-12-01',
'2021-01-01'],
dtype='datetime64[ns]', freq='BMS')

# BQS - 每一个季度末最后一月的第一个工做日
​
print(pd.date_range("2019", "2020", freq="BQS-JAN"))
print("")
print(pd.date_range("2019", "2020", freq="BQS-FEB"))
print("")
print(pd.date_range("2019", "2020", freq="BQS-MAR"))
print("")
print(pd.date_range("2019", "2020", freq="BQS-APR"))

DatetimeIndex(['2019-01-01', '2019-04-01', '2019-07-01', '2019-10-01',
'2020-01-01'],
dtype='datetime64[ns]', freq='BQS-JAN')
​
DatetimeIndex(['2019-02-01', '2019-05-01', '2019-08-01', '2019-11-01'], dtype='datetime64[ns]', freq='BQS-FEB')
​
DatetimeIndex(['2019-03-01', '2019-06-03', '2019-09-02', '2019-12-02'], dtype='datetime64[ns]', freq='BQS-MAR')
​
DatetimeIndex(['2019-01-01', '2019-04-01', '2019-07-01', '2019-10-01',
'2020-01-01'],
dtype='datetime64[ns]', freq='BQS-APR')

# BAS -- 每一年指定月份的第一个工做日
​
print(pd.date_range("2019", "2021", freq="BAS-JAN"))
print(pd.date_range("2019", "2021", freq="BAS-FEB"))
print(pd.date_range("2019", "2021", freq="BAS-DEC"))

DatetimeIndex(['2019-01-01', '2020-01-01', '2021-01-01'], dtype='datetime64[ns]', freq='BAS-JAN')
DatetimeIndex(['2019-02-01', '2020-02-03'], dtype='datetime64[ns]', freq='BAS-FEB')
DatetimeIndex(['2019-12-02', '2020-12-01'], dtype='datetime64[ns]', freq='BAS-DEC')

复合频率

# 7D 间隔是7天
​
pd.date_range("2019/10/1", "2019/12/1", freq="7D")

DatetimeIndex(['2019-10-01', '2019-10-08', '2019-10-15', '2019-10-22',
'2019-10-29', '2019-11-05', '2019-11-12', '2019-11-19',
'2019-11-26'],
dtype='datetime64[ns]', freq='7D')

# 2h30min 间隔是2小时30分钟
​
pd.date_range("2019/10/1 00:00:00", "2019/10/1 12:00:00", freq="2h30min")

DatetimeIndex(['2019-10-01 00:00:00', '2019-10-01 02:30:00',
'2019-10-01 05:00:00', '2019-10-01 07:30:00',
'2019-10-01 10:00:00'],
dtype='datetime64[ns]', freq='150T')

# 2M 每间隔2个月最后一个日历
​
pd.date_range("2019", "2021", freq="2M")

DatetimeIndex(['2019-01-31', '2019-03-31', '2019-05-31', '2019-07-31',
'2019-09-30', '2019-11-30', '2020-01-31', '2020-03-31',
'2020-05-31', '2020-07-31', '2020-09-30', '2020-11-30'],
dtype='datetime64[ns]', freq='2M')

asfreq 时间频率转换

ts = pd.Series(np.random.rand(4), index=pd.date_range("2019/1/1", "2019/1/4"))
print(ts)
print("\n")
​
# 这里是把D改成4H
print(ts.asfreq("4H"))
print("\n")
​
# method 插值模式 ffill 用以前值填充 bfill 用以后值填充
print(ts.asfreq("4H", method="ffill"))
print("\n")
​
print(ts.asfreq("4H", method="bfill"))

2019-01-01   0.610403
2019-01-02   0.416557
2019-01-03   0.821631
2019-01-04   0.699457
Freq: D, dtype: float64

2019-01-01 00:00:00   0.610403
2019-01-01 04:00:00         NaN
2019-01-01 08:00:00         NaN
2019-01-01 12:00:00         NaN
2019-01-01 16:00:00         NaN
2019-01-01 20:00:00         NaN
2019-01-02 00:00:00   0.416557
2019-01-02 04:00:00         NaN
2019-01-02 08:00:00         NaN
2019-01-02 12:00:00         NaN
2019-01-02 16:00:00         NaN
2019-01-02 20:00:00         NaN
2019-01-03 00:00:00   0.821631
2019-01-03 04:00:00         NaN
2019-01-03 08:00:00         NaN
2019-01-03 12:00:00         NaN
2019-01-03 16:00:00         NaN
2019-01-03 20:00:00         NaN
2019-01-04 00:00:00   0.699457
Freq: 4H, dtype: float64

2019-01-01 00:00:00   0.610403
2019-01-01 04:00:00   0.610403
2019-01-01 08:00:00   0.610403
2019-01-01 12:00:00   0.610403
2019-01-01 16:00:00   0.610403
2019-01-01 20:00:00   0.610403
2019-01-02 00:00:00   0.416557
2019-01-02 04:00:00   0.416557
2019-01-02 08:00:00   0.416557
2019-01-02 12:00:00   0.416557
2019-01-02 16:00:00   0.416557
2019-01-02 20:00:00   0.416557
2019-01-03 00:00:00   0.821631
2019-01-03 04:00:00   0.821631
2019-01-03 08:00:00   0.821631
2019-01-03 12:00:00   0.821631
2019-01-03 16:00:00   0.821631
2019-01-03 20:00:00   0.821631
2019-01-04 00:00:00   0.699457
Freq: 4H, dtype: float64

2019-01-01 00:00:00   0.610403
2019-01-01 04:00:00   0.416557
2019-01-01 08:00:00   0.416557
2019-01-01 12:00:00   0.416557
2019-01-01 16:00:00   0.416557
2019-01-01 20:00:00   0.416557
2019-01-02 00:00:00   0.416557
2019-01-02 04:00:00   0.821631
2019-01-02 08:00:00   0.821631
2019-01-02 12:00:00   0.821631
2019-01-02 16:00:00   0.821631
2019-01-02 20:00:00   0.821631
2019-01-03 00:00:00   0.821631
2019-01-03 04:00:00   0.699457
2019-01-03 08:00:00   0.699457
2019-01-03 12:00:00   0.699457
2019-01-03 16:00:00   0.699457
2019-01-03 20:00:00   0.699457
2019-01-04 00:00:00   0.699457
Freq: 4H, dtype: float64

超前/滞后数据 shift(正数): 数值后移--滞后 ，shift(负数): 数值前移--超前

ts = pd.Series(np.random.rand(4), index=pd.date_range("2019/1/1", "2019/1/4"))
print(ts)
print("\n")
​
print(ts.shift(1))
print("\n")
​
print(ts.shift(-2))
print("\n")
​
# 计算变化百分比 该时间戳的值与上一个时间戳的值相比
​
per = ts/ts.shift(1)
print(per)

2019-01-01   0.197884
2019-01-02   0.403093
2019-01-03   0.208341
2019-01-04   0.330873
Freq: D, dtype: float64

2019-01-01         NaN
2019-01-02   0.197884
2019-01-03   0.403093
2019-01-04   0.208341
Freq: D, dtype: float64

2019-01-01   0.208341
2019-01-02   0.330873
2019-01-03         NaN
2019-01-04         NaN
Freq: D, dtype: float64

2019-01-01         NaN
2019-01-02   2.037017
2019-01-03   0.516855
2019-01-04   1.588134
Freq: D, dtype: float64

shift(freq) 加上freq参数 对时间戳进行位移 而不是对数值进行位移

print(ts)
print("\n")
​
print(ts.shift(2, freq="D")) # 按天
print("\n")
​
print(ts.shift(2, freq="T")) # 按分钟

2019-01-01   0.197884
2019-01-02   0.403093
2019-01-03   0.208341
2019-01-04   0.330873
Freq: D, dtype: float64

2019-01-03   0.197884
2019-01-04   0.403093
2019-01-05   0.208341
2019-01-06   0.330873
Freq: D, dtype: float64

2019-01-01 00:02:00   0.197884 2019-01-02 00:02:00   0.403093 2019-01-03 00:02:00   0.208341 2019-01-04 00:02:00   0.330873 Freq: D, dtype: float64

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