Question

I have a dataframe in R looking like this:

 ...    vals         cat  ...
        1.2          TRUE
        1.6          FALSE
        5            TRUE

I like to modify the values in the “vals” column depending on if the factor in the cat
column is TRUE or false. Lets say I want to multiply the value in the vals column
with a factor (e.g 9) when the category of the same row says TRUE.

As result I would like to
have a copy of the original dataframe but with the modified values instead. Or a dataframe with one more column containing the original values if unmodified (FALSE) and the modified if cat
was TRUE.

Hope somebody could
give me a hand with this.

Best Regards Sab.

Answer 1

x <- data.frame(vals=c(11.2,9.1,2.1),cat=c(TRUE,FALSE,TRUE))

x
  vals   cat
1 11.2  TRUE
2  9.1 FALSE
3  2.1  TRUE

y <- x

y[y$cat,] <- x[x$cat,]*9

y
   vals cat
1 100.8   9
2   9.1   0
3  18.9   9