[R] How to sum and group data by DATE in data frame

[Mohamed Lajnef]

Hi Clair,
try to use this code

aggregate(toto$Income,by=list((substr(toto$Date,1,7))),sum)

Regards
mohamed

clair.crossupton at googlemail.com a écrit :
> Dear all,
>
> Lets say I have a data frame as follows:
>
>
>   
>> Date <- as.Date(c('2006-08-23', '2006-08-30', '2006-09-06', '2006-09-13', '2006-09-20'))
>> Income <- c(73.79, 72.46, 76.32, 72.43, 72.62)
>> data.frame(Date, Income)
>>     
>         Date Income
> 1 2006-08-23  73.79
> 2 2006-08-30  72.46
> 3 2006-09-06  76.32
> 4 2006-09-13  72.43
> 5 2006-09-20  72.62
>   
>
> is there a way to group the data by month (summing the values in each
> month), i.e.
>
> Date       Income
> 2006-08  146.25
> 2006-09  221.37
>
> Thanks in advance,
> C.C.
>
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>
>   


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