[R] data frame and cumulative sum

[R. Michael Weylandt]

??"cumulative sum" would almost certainly lead you to cumsum with only
a modicum of effort

Michael

On Wed, Dec 7, 2011 at 5:13 PM, Giovanni Azua <bravegag at gmail.com> wrote:
> Hello,
>
> I have a data frame that looks like this (containing interarrival times):
>
>> str(df)
> 'data.frame':   18233 obs. of  1 variable:
>  $ Interarrival: int  135 806 117 4 14 1 9 104 169 0 ...
>> head(df)
>  Interarrival
> 1          135
> 2          806
> 3          117
> 4            4
> 5           14
> 6            1
>>
>
> This corresponds to the time differences (in ms) of a poisson arrival process where Interarrival{i+1} = time_{i+1} - time_{i}
>
> I want to get the Time bin (in minutes) of every interarrival basically something like:
>
> 1) df$Time <- sum(of all df$Interarrival up to "this rownum") # cumulative sum
>
> 2) df$Time <- floor(df$Time / 60000) + 1
>
> then I should get the first minute of Interarrival having 1 and so forth. The problem is I have no idea how to accomplish 1) in R.
>
> Can anyone advice?
>
> Thanks in advance,
> Best regards,
> Giovanni
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.