Excluding most recent day from rolling sum












1














I have a pandas dataframe, excerpt shown below, of rainfall data. 'Pcp' is a one day total, which I have then used to calculate rolling cumulative totals of rainfall for the other periods of time leading up to the day of interest (3 days up to 28 days), using:



df['Pcp_3day'] = df['Pcp'].rolling(3).sum()


What I would like to achieve is a rolling total of n days prior to but not including the date of interest. In other words, at the moment, the rolling totals are being formed with rainfall totals from days 0, -1, -2, whereas I would like to exclude day 0 (the day of interest) and have a rolling total of days -1, -2, -3, i.e the three days leading up to it.



I am unsure as to whether this analogy is very clear, but if there is any advice out there, it would be hugely appreciated.



Thanks



                Pcp     Pcp_3day    Pcp_7day    Pcp_10day   Pcp_14day   Pcp_21day   Pcp_28day
date
2017-12-04 8.382 19.304 21.082 40.132 40.132 42.418 71.374
2017-12-05 12.192 20.574 33.020 42.164 52.324 52.578 81.534
2017-12-06 1.016 21.590 33.020 34.290 53.340 53.594 82.550
2017-12-07 12.700 25.908 45.466 46.990 66.040 66.040 95
2017-12-08 5.080 18.796 50.292 51.816 71.120 71.120 88.900









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  • It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
    – eaydin
    Nov 12 at 11:55










  • @eaydin noted and edited, thanks.
    – SHV_la
    Nov 12 at 11:59
















1














I have a pandas dataframe, excerpt shown below, of rainfall data. 'Pcp' is a one day total, which I have then used to calculate rolling cumulative totals of rainfall for the other periods of time leading up to the day of interest (3 days up to 28 days), using:



df['Pcp_3day'] = df['Pcp'].rolling(3).sum()


What I would like to achieve is a rolling total of n days prior to but not including the date of interest. In other words, at the moment, the rolling totals are being formed with rainfall totals from days 0, -1, -2, whereas I would like to exclude day 0 (the day of interest) and have a rolling total of days -1, -2, -3, i.e the three days leading up to it.



I am unsure as to whether this analogy is very clear, but if there is any advice out there, it would be hugely appreciated.



Thanks



                Pcp     Pcp_3day    Pcp_7day    Pcp_10day   Pcp_14day   Pcp_21day   Pcp_28day
date
2017-12-04 8.382 19.304 21.082 40.132 40.132 42.418 71.374
2017-12-05 12.192 20.574 33.020 42.164 52.324 52.578 81.534
2017-12-06 1.016 21.590 33.020 34.290 53.340 53.594 82.550
2017-12-07 12.700 25.908 45.466 46.990 66.040 66.040 95
2017-12-08 5.080 18.796 50.292 51.816 71.120 71.120 88.900









share|improve this question
























  • It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
    – eaydin
    Nov 12 at 11:55










  • @eaydin noted and edited, thanks.
    – SHV_la
    Nov 12 at 11:59














1












1








1







I have a pandas dataframe, excerpt shown below, of rainfall data. 'Pcp' is a one day total, which I have then used to calculate rolling cumulative totals of rainfall for the other periods of time leading up to the day of interest (3 days up to 28 days), using:



df['Pcp_3day'] = df['Pcp'].rolling(3).sum()


What I would like to achieve is a rolling total of n days prior to but not including the date of interest. In other words, at the moment, the rolling totals are being formed with rainfall totals from days 0, -1, -2, whereas I would like to exclude day 0 (the day of interest) and have a rolling total of days -1, -2, -3, i.e the three days leading up to it.



I am unsure as to whether this analogy is very clear, but if there is any advice out there, it would be hugely appreciated.



Thanks



                Pcp     Pcp_3day    Pcp_7day    Pcp_10day   Pcp_14day   Pcp_21day   Pcp_28day
date
2017-12-04 8.382 19.304 21.082 40.132 40.132 42.418 71.374
2017-12-05 12.192 20.574 33.020 42.164 52.324 52.578 81.534
2017-12-06 1.016 21.590 33.020 34.290 53.340 53.594 82.550
2017-12-07 12.700 25.908 45.466 46.990 66.040 66.040 95
2017-12-08 5.080 18.796 50.292 51.816 71.120 71.120 88.900









share|improve this question















I have a pandas dataframe, excerpt shown below, of rainfall data. 'Pcp' is a one day total, which I have then used to calculate rolling cumulative totals of rainfall for the other periods of time leading up to the day of interest (3 days up to 28 days), using:



df['Pcp_3day'] = df['Pcp'].rolling(3).sum()


What I would like to achieve is a rolling total of n days prior to but not including the date of interest. In other words, at the moment, the rolling totals are being formed with rainfall totals from days 0, -1, -2, whereas I would like to exclude day 0 (the day of interest) and have a rolling total of days -1, -2, -3, i.e the three days leading up to it.



I am unsure as to whether this analogy is very clear, but if there is any advice out there, it would be hugely appreciated.



Thanks



                Pcp     Pcp_3day    Pcp_7day    Pcp_10day   Pcp_14day   Pcp_21day   Pcp_28day
date
2017-12-04 8.382 19.304 21.082 40.132 40.132 42.418 71.374
2017-12-05 12.192 20.574 33.020 42.164 52.324 52.578 81.534
2017-12-06 1.016 21.590 33.020 34.290 53.340 53.594 82.550
2017-12-07 12.700 25.908 45.466 46.990 66.040 66.040 95
2017-12-08 5.080 18.796 50.292 51.816 71.120 71.120 88.900






python sum rolling






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edited Nov 12 at 11:58

























asked Nov 12 at 11:43









SHV_la

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  • It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
    – eaydin
    Nov 12 at 11:55










  • @eaydin noted and edited, thanks.
    – SHV_la
    Nov 12 at 11:59


















  • It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
    – eaydin
    Nov 12 at 11:55










  • @eaydin noted and edited, thanks.
    – SHV_la
    Nov 12 at 11:59
















It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
– eaydin
Nov 12 at 11:55




It would help others when you provide the data structure explicitly. In this case, that it is a pandas DataFrame.
– eaydin
Nov 12 at 11:55












@eaydin noted and edited, thanks.
– SHV_la
Nov 12 at 11:59




@eaydin noted and edited, thanks.
– SHV_la
Nov 12 at 11:59












1 Answer
1






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1














Try this:



df['Pcp_3day'] = df['Pcp'].shift().rolling(3).sum()





share|improve this answer





















  • And this is why I love stackoverflow, thank you @John
    – SHV_la
    Nov 12 at 12:01











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1 Answer
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1 Answer
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Try this:



df['Pcp_3day'] = df['Pcp'].shift().rolling(3).sum()





share|improve this answer





















  • And this is why I love stackoverflow, thank you @John
    – SHV_la
    Nov 12 at 12:01
















1














Try this:



df['Pcp_3day'] = df['Pcp'].shift().rolling(3).sum()





share|improve this answer





















  • And this is why I love stackoverflow, thank you @John
    – SHV_la
    Nov 12 at 12:01














1












1








1






Try this:



df['Pcp_3day'] = df['Pcp'].shift().rolling(3).sum()





share|improve this answer












Try this:



df['Pcp_3day'] = df['Pcp'].shift().rolling(3).sum()






share|improve this answer












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answered Nov 12 at 11:45









John Zwinck

150k16175286




150k16175286












  • And this is why I love stackoverflow, thank you @John
    – SHV_la
    Nov 12 at 12:01


















  • And this is why I love stackoverflow, thank you @John
    – SHV_la
    Nov 12 at 12:01
















And this is why I love stackoverflow, thank you @John
– SHV_la
Nov 12 at 12:01




And this is why I love stackoverflow, thank you @John
– SHV_la
Nov 12 at 12:01


















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