quosure in case_when and/or ifelse

Question

I am trying to sort out how to use a quosure (if that's the right tool) to pass variable names to either an if_else(...) or a case_when(...) inside a mutate command using a string argument passed from a function. A quick reproducible example that isolates my question:

#create a simple 3x3 tibble
library(tidyverse)
lev<-c("a","b","c")
a=seq(1,3)
test<-tibble("index"=lev,"raw"=as.numeric(a),"x2"=a*2, x3 = a*3)

Now, suppose I want to replace the value of "raw" with zero in cases where index=="a". I can do this with raw code:

test %>% 
  mutate(raw=case_when(
  (index=="a")~0,
  TRUE~raw
)
)

and I get output:

# A tibble: 3 x 4
  index   raw    x2    x3
  <chr> <dbl> <dbl> <dbl>
1 a         0     2     3
2 b         2     4     6
3 c         3     6     9

Perfect. I can do this in a function two different ways (if_else or case_when). First:

sending_test_cw<-function(data_sent)
{
  data_sent %>% 
    mutate(raw=case_when(
      (index=="a")~0,
      TRUE~raw)
    )
}

yielding output:

sending_test_cw(test)

R > sending_test_cw(test)
# A tibble: 3 x 4
  index   raw    x2    x3
  <chr> <dbl> <dbl> <dbl>
1 a         0     2     3
2 b         2     4     6
3 c         3     6     9

or, for case_when:

sending_test_ie<-function(data_sent)
{
  data_sent %>% 
    mutate(
    raw=ifelse(index=="a",0,raw))
}

R > sending_test_ie(test)
# A tibble: 3 x 4
  index   raw    x2    x3
  <chr> <dbl> <dbl> <dbl>
1 a         0     2     3
2 b         2     4     6
3 c         3     6     9

and, again, I get the intended output.

Now, I want to create a function that works when sending the name of the column in which the index is held, something like this:

sending_test_qu<-function(data_sent,index_id="index")
{
  index_quo<-enquo(index_id)
  data_sent %>% 
    #group_by(index)%>%
    mutate(
      raw=ifelse(!!index_quo=="a",0,raw),
      raw_2=case_when(
        (!!index_quo=="a")~0,
        TRUE~raw)
    )
}

sending_test_qu(test)

But, I can't get that work work.

sending_test_qu<-function(data_sent,index_id="index")
{
  index_quo<-enquo(index_id)
  data_sent %>% 
    #group_by(index)%>%
    mutate(
      raw=ifelse(!!index_quo=="a",0,raw),
      raw_2=case_when(
        (!!index_quo=="a")~0,
        TRUE~raw)
    )
}

sending_test_qu(test)

this produces output as follows:

R > sending_test_qu(test)
# A tibble: 3 x 5
  index   raw    x2    x3 raw_2
  <chr> <dbl> <dbl> <dbl> <dbl>
1 a         1     2     3     1
2 b         1     4     6     1
3 c         1     6     9     1

Any suggestions or quosure pointers welcome.

Answer 1

Convert to symbol with ensym as the input is string (or can also be unquoted), If the input is unquoted, enquo with !! can be used or more directly {{}}.

sending_test_qu<-function(data_sent,index_id="index")
{
  index_sym<- rlang::ensym(index_id)
  data_sent %>% 
    #group_by(across(all_of(index_id)))%>%
    mutate(
      raw=ifelse(!!index_sym=="a",0,raw),
      raw_2=case_when(
        (!!index_sym=="a")~0,
        TRUE~raw)
    )
}

testing

# default argument value for index_id
> sending_test_qu(test)
 A tibble: 3 × 5
  index   raw    x2    x3 raw_2
  <chr> <dbl> <dbl> <dbl> <dbl>
1 a         0     2     3     0
2 b         2     4     6     2
3 c         3     6     9     3
# pass as unquoted
> sending_test_qu(test, index)
# A tibble: 3 × 5
  index   raw    x2    x3 raw_2
  <chr> <dbl> <dbl> <dbl> <dbl>
1 a         0     2     3     0
2 b         2     4     6     2
3 c         3     6     9     3
# pass as string
> sending_test_qu(test, "index")
# A tibble: 3 × 5
  index   raw    x2    x3 raw_2
  <chr> <dbl> <dbl> <dbl> <dbl>
1 a         0     2     3     0
2 b         2     4     6     2
3 c         3     6     9     3