Formula inside Mutate and use of ~

Question

Let's say I have a data frame df

df = data.frame(col1 = c(1:5),col2 = c(2:6))

I want to transform col1 by adding 10 to each value.

I have found several ways to do it for example using the recode function

df %>% mutate(col1 = recode(col1, "1" = "11", "2"="12", "3"="13", "4"="14", "5"="15"))

or using mutate(across()) function. df %>% mutate(across(col1, ~.x +10)

So here are my questions :

What are the meanings of x and the . for ? I guess it means for every row of col1 take x and add 10 ?
What could be an easier way to do this transformation ?

Thank you

For one column you don't need `across`, you can do `df %>% mutate(col1 = col1 + 10)` — Ronak Shah, Aug 10 '21 at 08:38
Thanks ! I was so obsessed with the function that I forgot the basis. — Paul Donadieu, Aug 10 '21 at 08:46
Here is another link that might help you: https://stackoverflow.com/questions/68249625/understanding-the-dplyracross-function/68249687#68249687 — Anoushiravan R, Aug 10 '21 at 09:36

score 2 · Accepted Answer · answered Aug 11 '21 at 09:25

In this case, you don't need across since it is only for one column.

library(dplyr)

df %>% mutate(col1 = col1 + 10)

#  col1 col2
#1   11    2
#2   12    3
#3   13    4
#4   14    5
#5   15    6

1 Answers1