use dplyr mutate to create new columns based on a vector of column names

Question

I would like to take the log of some columns, and create new columns that are all named log[original column name].

The code below works, but how can I pass the vector called columnstolog into mutate? Thank you.

library(dplyr)
data(mtcars)

columnstolog <- c('mpg', 'cyl', 'disp', 'hp')

mtcars %>% mutate(logmpg = log(mpg))
mtcars %>% mutate(logcyl = log(cyl))

Answer 1

Use mutate_at, if you can bear with _log being appended to the original column names:

mtcars %>% mutate_at(columnstolog, funs(log = log(.)))

#    mpg cyl  disp  hp drat    wt  qsec vs am gear carb  mpg_log  cyl_log disp_log   hp_log
#1  21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4 3.044522 1.791759 5.075174 4.700480
#2  21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4 3.044522 1.791759 5.075174 4.700480
#3  22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1 3.126761 1.386294 4.682131 4.532599
#4  21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1 3.063391 1.791759 5.552960 4.700480
#5  18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2 2.928524 2.079442 5.886104 5.164786
# ...