I have a condition in case_when that should not be evaluated, but it is causing an error in my code. How can I only have this function run if the condition is TRUE?
library(dplyr)
#>
tibble(x = "10+20)",
y = FALSE) |>
mutate(prior = case_when(y ~ as.character(eval(parse(text = x))),
T ~ as.character(x)))
#> Error in `mutate()`:
#> ℹ In argument: `prior = case_when(y ~ as.character(eval(parse(text =
#> x))), T ~ as.character(x))`.
#> Caused by error in `case_when()`:
#> ! Failed to evaluate the right-hand side of formula 1.
#> Caused by error in `parse()`:
#> ! <text>:1:6: unexpected ')'
#> 1: 10+20)
#> ^
#> Backtrace:
#> ▆
#> 1. ├─dplyr::mutate(...)
#> 2. ├─dplyr:::mutate.data.frame(...)
#> 3. │ └─dplyr:::mutate_cols(.data, dplyr_quosures(...), by)
#> 4. │ ├─base::withCallingHandlers(...)
#> 5. │ └─dplyr:::mutate_col(dots[[i]], data, mask, new_columns)
#> 6. │ └─mask$eval_all_mutate(quo)
#> 7. │ └─dplyr (local) eval()
#> 8. ├─dplyr::case_when(y ~ as.character(eval(parse(text = x))), T ~ as.character(x))
#> 9. │ └─dplyr:::case_formula_evaluate(...)
#> 10. │ ├─base::withCallingHandlers(...)
#> 11. │ └─rlang::eval_tidy(pair$rhs, env = default_env)
#> 12. ├─base::eval(parse(text = x))
#> 13. ├─base::parse(text = x)
#> 14. └─base::.handleSimpleError(...)
#> 15. └─dplyr (local) h(simpleError(msg, call))
#> 16. └─rlang::abort(message, parent = cnd, call = error_call)
Created on 2024-09-06 with reprex v2.0.2
ifelse will not evaluate yes or no if the whole test vector is FALSE or TRUE respectively, so this works:
tibble(x = "10+20)",
y = FALSE) |>
mutate(prior = ifelse(y, as.character(eval(parse(text = x))), as.character(x)))
But you cannot do this element-wise, since you cannot partially evaluate a vector. So you need to use a non-vectorized if else structure in that case. E.g.
library(purrr)
tibble(x = c("10+20)", "10+20"),
y = c(FALSE, TRUE)) |>
mutate(prior = map2_chr(
x, y,
\(x, y) if (y) as.character(eval(parse(text = x))) else x
))