[R] Query - Merging and conditional replacement of values in a data frame

[Jim Lemon]

Hi Bhaskar,
Maybe:

df1 <-read.table(text="time v1  v2 v3
1     2   3  4
2     5   6  4
3     1   3  4
4     1   3  4
5     2   3  4
6     2   3  4",
header=TRUE)


df2 <-read.table(text="time v11  v12 v13
3     112   3  4
4     112   3  4",
header=TRUE)

for(time1 in df1$time) {
 time2<-which(df2$time==time1)
 if(length(time2)) df1[df1$time==time1,]<-df2[time2,]
}

Jim


On Sun, Feb 12, 2017 at 11:13 AM, Bhaskar Mitra
<bhaskar.kolkata at gmail.com> wrote:
> Hello Everyone,
>
> I have two data frames df1 and df2 as shown below. They
> are of different length. However, they have one common column - time.
>
> df1 <-
> time v1  v2 v3
> 1     2   3  4
> 2     5   6  4
> 3     1   3  4
> 4     1   3  4
> 5     2   3  4
> 6     2   3  4
>
>
> df2 <-
> time v11  v12 v13
> 3     112   3  4
> 4     112   3  4
>
> By matching the 'time' column in df1 and df2, I am trying to modify column
> 'v1' in df1 by replacing it
> with values in column 'v11' in df2. The modified df1 should look something
> like this:
>
> df1 <-
> time v1   v2 v3
> 1     2   3  4
> 2     5   6  4
> 3     112 3  4
> 4     112 3  4
> 5     2   3  4
> 6     2   3  4
>
> I tried to use the 'merge' function to combine df1 and df2 followed by
> the conditional 'ifelse' statement. However, that doesn't seem to work.
>
> Can I replace the values in df1 by not merging the two data frames?
>
> Thanks for your help,
>
> Regards,
> Bhaskar
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.