purrr over several inputs in R

map2 walks two vectors together; pmap walks a list of them.

library(purrr)

langs <- c("r", "python")
tpms <- c(96, 104)

print(map2_chr(langs, tpms, ~ paste0(.x, "=", .y)))

args <- list(lang = langs, tpm = tpms, stars = c(3L, 3L))
print(pmap_chr(args, function(lang, tpm, stars)
  sprintf("%s %d (%d stars)", lang, tpm, stars)))

walk2(langs, tpms, ~ cat(.x, .y, "\n"))
print(imap_chr(set_names(tpms, langs), ~ paste(.y, .x)))

How it works

1. map2 requires both inputs to be the same length.
2. pmap takes a list or a data frame of arguments.
3. walk is map for side effects, returning the input.

Keywords and builtins used here

• c
• cat
• function
• imap_chr
• library
• list
• map2_chr
• paste
• paste0
• pmap_chr
• print
• set_names
• sprintf
• walk2

The run, in numbers

Lines

13

Characters to type

366

Tokens

127

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 73 seconds.

Type this snippet

Step 2 of 4 in purrr, step 2 of 10 in Functional & text tools.

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