r - pass string stored in variable in dplyr function

Question

I want to supply a string stored in a variable as a new column name while performed a dplyr group_by function. How can I retrieve the value stored inside the variable, and not the name of the variable, as a string?

# store label name
l <- var_label(df$Q8b_1)

# group variable and supply label to new column based on mutate
# DOES NOT WORK
df %>%
  group_by( as_factor(Q8b_1) ) %>%
  summarise(n=n()) %>%
  na.omit() %>%
  mutate(pct = n/sum(n) * 100) %>% 
  rename(l = pct) %>% # use label inside l, not literal "l"

# result
 as_factor(Q8b_1)   n           l
                1 252  38.4732824
                2 261  39.8473282
                3 112  17.0992366
                4  25   3.8167939
                5   5   0.7633588
            Total 655 100.0000000

Your first line of code is a bit confusing. var_label is it from a separate package? — akrun
– akrun, Commented Jan 4, 2020 at 17:18

akrun · Accepted Answer · 2020-01-04 17:25:08Z

1

We can do the rename_at

library(dplyr)
df %>%
  group_by(Q8b_1 = as_factor(Q8b_1) ) %>%
  summarise(n=n()) %>%
  na.omit() %>%
  mutate(pct = n/sum(n) * 100) %>% 
  rename_at(vars(pct), ~ l)

Or use

  rename(!! l := pct)

edited Jan 4, 2020 at 17:25

answered Jan 4, 2020 at 16:47

akrun

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3 Comments

eric s Over a year ago

The second option worked, but the first threw an error: Unknown column Research ("Research" is the value stored in l)

akrun Over a year ago

@erics I think the issue is because of not quoting the 'pct'. I was thinking that it is also from a stored object

akrun Over a year ago

@erics Ok, i think in rename_at, it should be reverse rename_at(vars(pct), ~ l)

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