Python 修改Pandas dataframe以列出年、月和日期
我想在下面修改我正在创建的数据框:Python 修改Pandas dataframe以列出年、月和日期,python,pandas,Python,Pandas,我想在下面修改我正在创建的数据框: from datetime import date from dateutil.rrule import rrule, DAILY, YEARLY from dateutil.relativedelta import * import pandas START_YR = 2010 END_YR = 2013 strt_date = datetime.date(START_YR, 1, 1) end_date = datetime.date(END_YR,
from datetime import date
from dateutil.rrule import rrule, DAILY, YEARLY
from dateutil.relativedelta import *
import pandas
START_YR = 2010
END_YR = 2013
strt_date = datetime.date(START_YR, 1, 1)
end_date = datetime.date(END_YR, 12, 31)
dt = rrule(DAILY, dtstart=strt_date, until=end_date)
serie_1 = pandas.Series(np.random.randn(dt.count()), \
index = pandas.date_range(strt_date, end_date))
如何创建以年、月和日期为独立列的数据框?将序列转换为数据框,然后将新列添加为周期。 如果您只想将月份作为整数,请参见“month_int”示例
df = pd.DataFrame(serie_1)
df['month'] = [ts.to_period('M') for ts in df.index]
df['year'] = [ts.to_period('Y') for ts in df.index]
df['month_int'] = [ts.month for ts in df.index]
>>> df
Out[16]:
0 month year month_int
2010-01-01 0.332370 2010-01 2010 1
2010-01-02 -0.036814 2010-01 2010 1
2010-01-03 1.751511 2010-01 2010 1
... ... ... ... ...
2013-12-29 0.345707 2013-12 2013 12
2013-12-30 -0.395924 2013-12 2013 12
2013-12-31 -0.614565 2013-12 2013 12
将序列转换为数据帧,然后添加新列作为句点。 如果您只想将月份作为整数,请参见“month_int”示例
df = pd.DataFrame(serie_1)
df['month'] = [ts.to_period('M') for ts in df.index]
df['year'] = [ts.to_period('Y') for ts in df.index]
df['month_int'] = [ts.month for ts in df.index]
>>> df
Out[16]:
0 month year month_int
2010-01-01 0.332370 2010-01 2010 1
2010-01-02 -0.036814 2010-01 2010 1
2010-01-03 1.751511 2010-01 2010 1
... ... ... ... ...
2013-12-29 0.345707 2013-12 2013 12
2013-12-30 -0.395924 2013-12 2013 12
2013-12-31 -0.614565 2013-12 2013 12
仅访问属性将大大加快速度:
df['date'] = df.index.date
df['year'] = df.index.year
df['month'] = df.index.month
将计时与列表理解方法进行比较:
In [25]:
%%timeit
df['month'] = [ts.to_period('M') for ts in df.index]
df['year'] = [ts.to_period('Y') for ts in df.index]
df['month_int'] = [ts.month for ts in df.index]
1 loops, best of 3: 664 ms per loop
In [26]:
%%timeit
df['date'] = df.index.date
df['year'] = df.index.year
df['month'] = df.index.month
100 loops, best of 3: 5.96 ms per loop
因此,使用datetime属性的速度快了100倍以上仅访问属性的速度将大大加快:
df['date'] = df.index.date
df['year'] = df.index.year
df['month'] = df.index.month
将计时与列表理解方法进行比较:
In [25]:
%%timeit
df['month'] = [ts.to_period('M') for ts in df.index]
df['year'] = [ts.to_period('Y') for ts in df.index]
df['month_int'] = [ts.month for ts in df.index]
1 loops, best of 3: 664 ms per loop
In [26]:
%%timeit
df['date'] = df.index.date
df['year'] = df.index.year
df['month'] = df.index.month
100 loops, best of 3: 5.96 ms per loop
因此,使用datetime属性快100倍以上是的,属性的执行速度更快,但周期在熊猫生态系统中发挥的作用更好(例如,绘图、分组等)。句点存储为对象(因此占用更多内存),不容易保存到数据库。两种方法之间的使用取决于偏好和数据量。是的,属性执行速度更快,但周期对熊猫生态系统的影响更大(例如,绘图、分组等)。句点存储为对象(因此占用更多内存),不容易保存到数据库。两种方法之间的使用取决于偏好和数据量。