Pass column names as strings to group_by and summarize
For this you can now use _at
versions of the verbs
df %>%
group_by_at(cols2group) %>%
summarize_at(.vars = col2summarize, .funs = min)
Edit (2021-06-09):
Please see Ronak Shah's answer, using
mutate(across(all_of(cols2summarize), min))
Now the preferred option
Another option is to use non-standard evaluation (NSE), and have R interpret the string as quoted names of objects:
cols2group <- c("x","y")
col2summarize <- "z"
df %>%
group_by(!!rlang::sym(cols2group)) %>%
summarize(min(!!rlang::sym(col2summarize)))
The rlang::sym()
function takes the strings and turns them into quotes, which are in turn unquoted by !!
and used as names in the context of df
where they refer to the relevant columns. There's different ways of doing the same thing, as always, and this is the shorthand I tend to use!
From dplyr
1.0.0 you can use across
:
library(dplyr)
cols2group <- c("x","y")
col2summarize <- "z"
df %>%
group_by(across(all_of(cols2group))) %>%
summarise(across(all_of(col2summarize), min)) %>%
ungroup
# x y z
# <chr> <dbl> <int>
#1 a 1 1
#2 a 2 3
#3 b 2 4
#4 b 3 5