Package 'loopurrr'

Description

as_loop() takes a function call to one of {purrr}'s iterator functions, such as purrr::map(), and translates it into a regular for loop. Depending on the output context, the translation is either (i) printed to the console, (ii) copied to the clipboard or (iii) directly inserted into RStudio. Note that the latter two options require the {clipr} respectively the {rstudioapi} package to be installed.

The usage is pretty straight-forward: Just wrap a call to a {purrr} iterator function into as_loop() or us one of the pipe operators (⁠|>⁠ or ⁠%>%⁠) to pipe the function call into as_loop(). For details see the examples below.

Usage

as_loop(
  .expr,
  simplify = TRUE,
  output_nm = "out",
  idx = "i",
  output_context = default_context(),
  return = c("string", "eval")
)

Arguments

Value

Depending on the return argument the return value is:

1. When output = "string": NULL. As a side-effect, the translated for loop will be returned to the specified output context.

2. When output = "eval": Usually the return value of the output object that is constructed with the for loop. In case of a call to walk, walk2 etc. the (first) input object will be returned.

Supported functions

The following iterator functions from the {purrr} package are currently supported:

options(width = 60)
get_supported_fns("as_loop")
#> $map
#>  [1] "map"     "map_at"  "map_chr" "map_dbl" "map_df" 
#>  [6] "map_dfc" "map_dfr" "map_if"  "map_int" "map_lgl"
#> [11] "map_raw"
#> 
#> $imap
#> [1] "imap"     "imap_chr" "imap_dbl" "imap_dfc" "imap_dfr"
#> [6] "imap_int" "imap_lgl" "imap_raw"
#> 
#> $map
#> [1] "map2"     "map2_chr" "map2_dbl" "map2_df"  "map2_dfc"
#> [6] "map2_dfr" "map2_int" "map2_lgl" "map2_raw"
#> 
#> $pmap
#> [1] "pmap"     "pmap_chr" "pmap_dbl" "pmap_df"  "pmap_dfc"
#> [6] "pmap_dfr" "pmap_int" "pmap_lgl" "pmap_raw"
#> 
#> $lmap
#> [1] "lmap"    "lmap_at"
#> 
#> $modify
#> [1] "modify"    "modify_at" "modify_if" "modify2"  
#> [5] "imodify"  
#> 
#> $walk
#> [1] "iwalk" "pwalk" "walk"  "walk2"
#> 
#> $accumulate
#> [1] "accumulate"  "accumulate2"
#> 
#> $reduce
#> [1] "reduce"  "reduce2"

Examples

If we wrap or pipe a call to purrr::map() into as_loop() it will be translated into a regular for loop. Depending on the output context, the resulting for loop will either be (i) inserted directly into a script in RStudio, (ii) copied to the clipboard or (iii) printed to the console.

x <- list(1, c(1:2), c(1:3))
as_loop(map(x, sum))        # wrap a call in `as_loop()`
map(x, sum) %>% as_loop() # pipe a call into `as_loop()`

# --- convert: `map(x, sum)` as loop --- #
out <- vector("list", length = length(x))

for (i in seq_along(x)) {
  out[[i]] <- sum(x[[i]])
}
# --- end loop --- #

The output_nm argument lets us specify the name of the resulting output object. In the example below ".res". The idx argument lets us specify the index to be used. In the example below "j".

x <- list(1, c(1:2), c(1:3))
map_dbl(x, sum) %>%
  as_loop(., output_nm = ".res", idx = "j")

# --- convert: `map_dbl(x, sum)` as loop --- #
.res <- vector("double", length = length(x))

for (j in seq_along(x)) {
  .res[[j]] <- sum(x[[j]])
}
# --- end loop --- #

When simplify is set FALSE as_loop will neither check the validity of the underlying call nor the expected output. In this case the resulting for loop is more verbose. This is because we need to take the case of NULL in the return values into account. In the example below we further see what happens, when we use an unnamed object, such as 1:3, in the call to purrr::map(). as_loop() assign unnamed objects an internal name. In the example below .inp1.

map(1:3, sum) %>% as_loop(., simplify = FALSE)

# --- convert: `map(1:3, sum)` as loop --- #
.inp1 <- 1:3
out <- vector("list", length = length(.inp1))

for (i in seq_along(.inp1)) {
  .tmp <- sum(.inp1[[i]])
  if (!is.null(.tmp))
    out[[i]] <- .tmp
}
# --- end loop --- #

Description

get_output_opt() and set_output_opt() get and set loopurrr's output options. They are light wrappers around getOption("loopurrr.output") and options("loopurrr.output").

default_context() inspects if the "loopurrr.output" option is set. If the option is not specified, it will default to c("rstudio", "clipboard", "console"). If "console" is not among the output options it will be automatically included as last option.

Usage

get_output_opt(default = NULL)

set_output_opt(x = list("rstudio", "clipboard", "console", NULL))

default_context()

Arguments

Value

For get_output_opt(), the current value set for option "loopurrr.output", or default (which defaults to NULL) if the option is unset.

For default_context(), either the current value set for option "loopurrr.output". In this case, if "console" is not among the options, it will be automatically included as last option. Or, if option "loopurrr.output" is not specified c("rstudio", "clipboard", "console").

Examples

set_output_opt(c("clipboard", "rstudio"))

get_ouptut_opt()
#> [1] "clipboard" "rstudio"

default_context()
#> [1] "clipboard" "rstudio" "console"

Description

get_supported_fns() shows which functions are supported for a specific {loopurrr} function. Currently, only works on as_loop().

Usage

get_supported_fns(fn)

Arguments

Value

A list of supported function names as named character vectors.

Examples

options(width = 60)
get_supported_fns("as_loop")
#> $map
#>  [1] "map"     "map_at"  "map_chr" "map_dbl" "map_df" 
#>  [6] "map_dfc" "map_dfr" "map_if"  "map_int" "map_lgl"
#> [11] "map_raw"
#> 
#> $imap
#> [1] "imap"     "imap_chr" "imap_dbl" "imap_dfc" "imap_dfr"
#> [6] "imap_int" "imap_lgl" "imap_raw"
#> 
#> $map
#> [1] "map2"     "map2_chr" "map2_dbl" "map2_df"  "map2_dfc"
#> [6] "map2_dfr" "map2_int" "map2_lgl" "map2_raw"
#> 
#> $pmap
#> [1] "pmap"     "pmap_chr" "pmap_dbl" "pmap_df"  "pmap_dfc"
#> [6] "pmap_dfr" "pmap_int" "pmap_lgl" "pmap_raw"
#> 
#> $lmap
#> [1] "lmap"    "lmap_at"
#> 
#> $modify
#> [1] "modify"    "modify_at" "modify_if" "modify2"  
#> [5] "imodify"  
#> 
#> $walk
#> [1] "iwalk" "pwalk" "walk"  "walk2"
#> 
#> $accumulate
#> [1] "accumulate"  "accumulate2"
#> 
#> $reduce
#> [1] "reduce"  "reduce2"