[R] lag, count

[Rui Barradas]

I forgot about the sorting part and assumed the data.frame was already 
sorted. If not, after converting y2 to class Date, you can do

lag <- lag[order(lag$ID, lag$y2), ]

Rui Barradas

Em 15-10-2016 19:45, Rui Barradas escreveu:
> Hello,
>
> Try the following.
>
>
> lag<-read.table(text=" ID, y1, y2
> 1,0,12/25/2014
> 1,125,9/15/2015
> 1,350,1/30/2016
> 2,0,12/25/2012
> 2,450,9/15/2014
> 2,750,1/30/2016
> 2,  656, 11/30/2016
> ",sep=",",header=TRUE)
>
> str(lag)
> lag$y2 <- as.Date(lag$y2, format = "%m/%d/%Y")
> str(lag)
>
> # 1)
> flag <- ave(lag$ID, lag$ID, FUN = seq_along)
> lag2 <- cbind(lag[1], flag, lag[-1])
>
> # 2)
> y1dif <- ave(lag2$y1, lag2$ID, FUN = function(y) c(0, y[-1] -
> y[-length(y)]))
> y2dif <- unlist(tapply(lag2$y2, lag2$ID, FUN = function(y) c(0, y[-1] -
> y[-length(y)])))
>
> lag2 <- cbind(lag2, y1dif, y2dif)
> lag2
>
> Hope this helps,
>
> Rui Barradas
>
> Em 15-10-2016 17:57, Val escreveu:
>> Hi all,
>>
>> I want sort the data by ID and Y2 then count the number of rows within
>> IDs.  Assign a "flag" variable to reach row starting from first  to
>> the last row.
>> For instance, in the following data ID "1" has three rows   and each
>> row is assigned flag sequentially 1, 2,3.
>>
>> 2. In the second step, within each ID, I want get the difference
>> between the subsequent row values of y1 and y2(date) values.
>> Within each ID the first value of y1diff  and y2diff are always 0. The
>> second values for each will  be the current row minus the previous
>> row.
>>
>>
>>
>> lag<-read.table(text=" ID, y1, y2
>> ID,Y1,y2
>> 1,0,12/25/2014
>> 1,125,9/15/2015
>> 1,350,1/30/2016
>> 2,0,12/25/2012
>> 2,450,9/15/2014
>> 2,750,1/30/2016
>> 2,  656, 11/30/2016
>> ",sep=",",header=TRUE)
>>
>> output looks like as follows
>>
>> ID,flag,y1,y2,y1dif,y2dif
>> 1,1,0,12/25/2014,0,0
>> 1,2,125,9/15/2015,125,264
>> 1,3,350,1/30/2016,225,137
>> 2,1,0,12/25/2012,0,0
>> 2,2,450,9/15/2014,450,629
>> 2,3,750,1/30/2016,300,502
>> 2, 4, 656 11/30/2016, -94, 305
>>
>> Thank you
>>
>
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