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

[Bhaskar Mitra]

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

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