Pandas Timedelta 以天为单位

问题描述

我在 pandas 中有一个名为munged_data"的数据框，其中包含两列entry_date"和dob"，我已使用 pd.to_timestamp 将其转换为时间戳.我试图弄清楚如何根据时间计算人的年龄'entry_date' 和 'dob' 之间的区别，要做到这一点，我需要得到两列之间的天数差异(这样我就可以像 round(days/365.25) 一样做一些事情.我似乎无法找到一种使用矢量化操作的方法.当我执行 munged_data.entry_date-munged_data.dob 时，我得到以下信息:

I have a dataframe in pandas called 'munged_data' with two columns 'entry_date' and 'dob' which i have converted to Timestamps using pd.to_timestamp.I am trying to figure out how to calculate ages of people based on the time difference between 'entry_date' and 'dob' and to do this i need to get the difference in days between the two columns ( so that i can then do somehting like round(days/365.25). I do not seem to be able to find a way to do this using a vectorized operation. When I do munged_data.entry_date-munged_data.dob i get the following :

internal_quote_id
2                    15685977 days, 23:54:30.457856
3                    11651985 days, 23:49:15.359744
4                     9491988 days, 23:39:55.621376
7                     11907004 days, 0:10:30.196224
9                    15282164 days, 23:30:30.196224
15                  15282227 days, 23:50:40.261632

但是我似乎无法将天数提取为整数，以便我可以继续计算.任何帮助表示赞赏.

However i do not seem to be able to extract the days as an integer so that i can continue with my calculation.Any help appreciated.

推荐答案

你需要 0.11 这个(0.11rc1 已经出来了，下周最后的问题)

You need 0.11 for this (0.11rc1 is out, final prob next week)

In [9]: df = DataFrame([ Timestamp('20010101'), Timestamp('20040601') ])

In [10]: df
Out[10]:
                    0
0 2001-01-01 00:00:00
1 2004-06-01 00:00:00

In [11]: df = DataFrame([ Timestamp('20010101'),
                          Timestamp('20040601') ],columns=['age'])

In [12]: df
Out[12]:
                  age
0 2001-01-01 00:00:00
1 2004-06-01 00:00:00

In [13]: df['today'] = Timestamp('20130419')

In [14]: df['diff'] = df['today']-df['age']

In [16]: df['years'] = df['diff'].apply(lambda x: float(x.item().days)/365)

In [17]: df
Out[17]:
                  age               today                diff      years
0 2001-01-01 00:00:00 2013-04-19 00:00:00 4491 days, 00:00:00  12.304110
1 2004-06-01 00:00:00 2013-04-19 00:00:00 3244 days, 00:00:00   8.887671

最后你需要这个奇怪的应用程序，因为还没有完全支持 timedelta64[ns] 标量(例如，我们现在如何使用时间戳来处理 datetime64[ns]，在 0.12 中)

You need this odd apply at the end because not yet full support for timedelta64[ns] scalars (e.g. like how we use Timestamps now for datetime64[ns], coming in 0.12)

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