Using gsub adding new column in a data.table

Question

Sorry for a very basic question, solution must be very simple but I\'m not able to find it.

Trying to use gsub adding a new column in a data.table, I got the warning

Answer 1

The easiest approach would be to use a string processing package that has vectorized arguments, like stringi:

library(stringi)
dt[, v3 := stri_replace_all_fixed(v2, "x", v1)][]
#    v1     v2     v3
# 1:  1    axb    a1b
# 2:  2   cxxd   c22d
# 3:  3 exfxgx e3f3g3

---

Alternatively, you can make your own "vectorized" version of gsub by using the Vectorize function:

vGsub <- Vectorize(gsub, vectorize.args = c("replacement", "x"))
dt[, v3 := vGsub("x", v1, v2)][]
#    v1     v2     v3
# 1:  1    axb    a1b
# 2:  2   cxxd   c22d
# 3:  3 exfxgx e3f3g3

Answer 2

dt[, v3 := gsub("x", v1, v2), by = v1]