数据分析 ——— pandas日期处理（五）

# pandas日期处理
import pandas as pd
import numpy as np

# data.range() 创建日期序列
print(pd.date_range('1/1/2011', periods=5))
"""
输出：
DatetimeIndex(['2011-01-01', '2011-01-02', 
                '2011-01-03', '2011-01-04',
                 '2011-01-05'],
              dtype='datetime64[ns]', freq='D')
"""

# 更改日期频率
# 按月，输出每月的1号的前一天
print(pd.date_range('1/1/2011', periods=5, freq='M')) 
"""
输出：
DatetimeIndex(['2011-01-31', '2011-02-28', 
                '2011-03-31', '2011-04-30',
               '2011-05-31'],
              dtype='datetime64[ns]', freq='M')
"""

# bdate_range() 商业日期范围，不包括周六和周天
print(pd.bdate_range('8/2/2019', periods=5))
"""
输出：
DatetimeIndex(['2019-08-02', '2019-08-05', 
              '2019-08-06', '2019-08-07',
               '2019-08-08'],
              dtype='datetime64[ns]', freq='B')
"""

import pandas as pd
import numpy as np
start = pd.datetime(2019, 8,2)
end = pd.datetime(2019, 8, 8)
print(pd.date_range(start, end))
"""
输出：
DatetimeIndex(['2019-08-02', '2019-08-03', 
              '2019-08-04', '2019-08-05',
               '2019-08-06', '2019-08-07',
                '2019-08-08'],
              dtype='datetime64[ns]', freq='D')
"""

import pandas as pd
# 通过传递字符串文字，我们可以创建一个timedelta对象。

print( pd.Timedelta('2 days 9 hours 15 minutes 30 seconds'))
"""
输出：
2 days 09:15:30
"""

# 通过用单位传递一个整数值，一个参数会创建一个Timedelta对象。
print(pd.Timedelta(6, unit='h'))
"""
输出：
0 days 06:00:00
"""

"""
数据偏移，诸如 - 周，日，小时，分钟，秒，毫秒，微秒，纳秒等
数据偏移量也可用于构建。
"""
print(pd.Timedelta(days=2))
"""
输出：
2 days 00:00:00
"""

import datetime

print('the Date tody is:', datetime.datetime.today())
"""
输出：
the Date tody is: 2019-08-07 06:52:15.732195
"""

# 当前的年月份，星期
date_today = datetime.date.today() 
print(date_today) 
print('this year:',date_today.year) 
print('this Month:',date_today.month)
print('month name:',date_today.strftime('%B')) 
print('this week day:',date_today.day) 
print('week day Name:',date_today.strftime('%A'))
"""
输出：
2019-08-07
this year: 2019
this Month: 8
month name: August
this week day: 7
week day Name: Wednesday
"""

# 日期时间算术
day1 = datetime.date(2019, 8, 7)
print('day1:', day1.ctime())

day2 = datetime.date(1995, 5, 12)
print('day2:', day2.ctime())

print('number of days:', day1-day2)
"""
输出：
day1: Wed Aug  7 00:00:00 2019
day2: Fri May 12 00:00:00 1995
number of days: 8853 days, 0:00:00

"""

date_today = datetime.date.today()

no_df_days =  datetime.timedelta(days =4)
before_four_days = date_today-no_df_days
print("before four days:", before_four_days)
"""
输出：
before four days: 2019-08-03
"""

after_four_days =  date_today + no_df_days
print("after fours days:", after_four_days)
"""
输出：
after fours days: 2019-08-11
"""

# 时间的比较
date_today =  datetime.date.today()
no_of_days = datetime.timedelta(days=4)
before_four_days = date_today-no_df_days
after_four_days =  date_today + no_df_days

date1 = datetime.date(2018, 6, 6)

print('date1:', date1)

if date1 == before_four_days:
    print('same dates')
if date_today > date1:
    print('past Date')
if date1 < after_four_days:
    print('future date')
"""
输出：
date1: 2018-06-06
past Date
future date
"""