fassplyr

⚠️ This package is LLM-generated. The builder preprocessor it depends on is not.

A builder plugin that translates dplyr pipe chains to data.table syntax at build time.

Write idiomatic dplyr in your source files, get idiomatic data.table in your package: it uses builder to translate the code at build time.

🔴 This is a simple text repalcement (no AST parsing) so it's not perfect, consider this a proof of concept.

Usage

In your srcr/ source files, wrap dplyr pipe chains with #> fassplyr / #> endfassplyr markers:

library(data.table)

m <- mtcars

#> fassplyr
m |>
  dplyr::group_by(cyl) |>
  dplyr::summarise(mean_mpg = mean(mpg)) |>
  dplyr::arrange(dplyr::desc(mean_mpg))
#> endfassplyr

After running builder, the output in R/ becomes:

library(data.table)

m <- mtcars

data.table::as.data.table(m)[, .(mean_mpg = mean(mpg)), by = .(cyl)][order(-mean_mpg)]

Setup

Add the plugin to your builder.ini:

plugin: fassplyr::plugin

Or pass it to the CLI with the -plugin fassplyr::plugin.

Supported Verbs

dplyr	data.table
dplyr::filter(cond1, cond2)	[cond1 & cond2]
dplyr::select(col1, col2)	[, .(col1, col2)]
dplyr::mutate(a = expr)	[, :=(a = expr)]
dplyr::summarise(a = expr)	[, .(a = expr)]
dplyr::arrange(x, dplyr::desc(y))	[order(x, -y)]
dplyr::group_by(g)	by = .(g) on the next verb
dplyr::slice(1, 3)	[c(1, 3)]
dplyr::distinct(col1, col2)	unique(...[, .(col1, col2)])

dplyr::n() is replaced with .N. dplyr::desc(x) is replaced with -x inside arrange. Both n() and desc() also work without the dplyr:: prefix.

summarize (American spelling) is accepted as an alias for summarise.

Rules

• Only the |> (native) pipe is supported
• Verbs must use the dplyr:: prefix — bare verbs like filter() are not supported
• Unrecognized verbs produce a warning and are passed through as comments

Not Supported

This is a proof of concept. The following are not handled:

• %>% (magrittr pipe)
• tidyselect helpers (starts_with(), everything(), where(), etc.)
• Negative selection in select()
• across() / c_across()
• ungroup()
• .data$ pronoun
• Joins (left_join, inner_join, etc.)