Hi R users,
I have a test dataframe ("file1," shown below) for which I am trying
to create a flag for the first and last ID record (equivalent to SAS
first.id and last.id variables.
Dump of file1:
> file1
id rx week dv1
1 1 1 1 1
2 1 1 2 1
3 1 1 3 2
4 2 1 1 3
5 2 1 2 4
6 2 1 3 1
7 3 1 1 2
8 3 1 2 3
9 3 1 3 4
10 4 1 1 2
11 4 1 2 6
12 4 1 3 5
13 5 2 1 7
14 5 2 2 8
15 5 2 3 5
16 6 2 1 2
17 6 2 2 4
18 6 2 3 6
19 7 2 1 7
20 7 2 2 8
21 8 2 1 9
22 9 2 1 4
23 9 2 2 5
I have written code that correctly assigns the first.id and last.id variabes:
require(Hmisc) #for Lags
#ascending order to define first dot
file1<- file1[order(file1$id, file1$week),]
file1$first.id <- (Lag(file1$id) != file1$id)
file1$first.id[1]<-TRUE #force NA to TRUE
#descending order to define last dot
file1<- file1[order(-file1$id,-file1$week),]
file1$last.id <- (Lag(file1$id) != file1$id)
file1$last.id[1]<-TRUE #force NA to TRUE
#resort to original order
file1<- file1[order(file1$id,file1$week),]
I am now trying to get the above code to work as a function, and am
clearly doing something wrong:
> first.last <- function (df, idvar, sortvars1, sortvars2)
+ {
+ #sort in ascending order to define first dot
+ df<- df[order(sortvars1),]
+ df$first.idvar <- (Lag(df$idvar) != df$idvar)
+ #force first record NA to TRUE
+ df$first.idvar[1]<-TRUE
+
+ #sort in descending order to define last dot
+ df<- df[order(-sortvars2),]
+ df$last.idvar <- (Lag(df$idvar) != df$idvar)
+ #force last record NA to TRUE
+ df$last.idvar[1]<-TRUE
+
+ #resort to original order
+ df<- df[order(sortvars1),]
+ }
>
Function call:
> first.last(df=file1, idvar=file1$id,
sortvars1=c(file1$id,file1$week), sortvars2=c(-file1$id,-file1$week))
R Error:
Error in as.vector(x, mode) : invalid argument 'mode'
>
I am not sure about the passing of the sort strings. Perhaps this is
were things are off. Any help greatly appreciated.
Thanks,
Gerard
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