[R] using diff function with by function

[Rui Barradas]

Hello,

Maybe you want

by(tr$srv_dt, tr$Rmbr, diff, lag=1, difference=1)


Can't you ?dput a data example?

dput(head(tr, 30))  # paste the output of this in a post


Hope this helps,

Rui Barradas

Em 10-03-2014 16:10, Mckinstry, Craig escreveu:
> I have been trying to process a data.frame (tr) on a grouping factor (Rmbr) using diff
> to find differences between srv_dt (a date) by Rmbr and keep getting the following error message
>
>> tmp <- by(tr,tr$Rmbr, diff, tr$srv_dt, lag=1, difference=1)
> Error in r[i1] - r[-length(r):-(length(r) - lag + 1L)] :
>    non-numeric argument to binary operator
> # the only two arguments I supply are both numeric
>> mode(tr$srv_dt)
> [1] "numeric"
>> mode(tr$Rmbr)
> [1] "numeric"
>
>
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