Learn R Programming

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sig prints R functions signatures and writes them to file. (In this case, signature means the name and arguments, with possible defaults, of that function.)

To load the package, type

library(sig)

If you want to know how to call a function, just pass a function to the sig function. For example,

sig(mean)
#mean <- function(x, ...)
sig(mean.default)
#mean.default <- function(x, trim = 0, na.rm = FALSE, ...)

If you pass an anonymous function, it is given the name ..anonymous...

sig(function(x, y) {x + y})
#..anonymous.. <- function(x, y)

You can override the name of the function by passing a second argument. This is useful when using sig with an *apply function.

fn_list <- list(
  mean = mean, 
  var = var
)
lapply(fn_list, sig)         #names are a mess
mapply(                      #use mapply for lists
  sig, 
  fn_list, 
  names(fn_list), 
  SIMPLIFY = FALSE
)

"Black Box" is a useful game for testing how maintainable your code is. You give your friend or colleague the signatures of your functions and have them guess what the function contents. For example, if you show them

mean <- function(x, ...)

then they might be able to guess that the function calculates the arithmetic mean of a numeric input.

If you didn't know what it was, the signature for the lm function doesn't make it as clear what the function does

sig(lm)
#lm <- function(formula, data, subset, weights, na.action, method =
#  "qr", model = TRUE, x = FALSE, y = FALSE, qr = TRUE, singular.ok =
#  TRUE, contrasts = NULL, offset, ...)

Your friend might guess that since the function takes a formula and a data arguement that it is some kind of model. Some of the other arguments may be guessable. "Oh, weights must let you run a weighted model!" Beyond that, the function's purpose is difficult to determine without consulting documentation.

In general, if you can guess what a function does, and what its body should contain, based only on the signature, then that function will be easy to use and easy to maintain. By contrast, an unclear function signature provides a warning that it may be difficult to use or maintain.

To make Black Box easy to play, use the write_sigs function to write all the functions from a file or R package to a text file.

#From an environment
write_sigs(
  pkg2env(graphics), 
  "graphics pkg sigs.R"
)

#From a file
write_sigs(
  "my R file.R",
  "my sigs.R
)

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Version

Install

install.packages('sig')

Monthly Downloads

230

Version

0.0-5

License

Unlimited

Maintainer

Richard Cotton

Last Published

January 22nd, 2015

Functions in sig (0.0-5)

as.siglist

Coerce object to be a siglist
exponential_cut

Cut with exponential breaks
print_engine

Workhorse of the print methods
is.siglist

Is the input a siglist?
list_sigs

List the signatures of all functions
sig_report

Summarise function complexity of a file or environment
fix_fn_names

Fix names for sigs
source_to_new_env

Source a file into a new environment.
[

Indexing for siglists
toString.siglist

Print a siglist object
sig

Generate a function signature object
toString.sig

Print a sig object
as.sig

Coerce object to be a sig
is.sig

Is the input a sig?
backquote

Wrap in backquotes
write_sigs

Write sigs to file
pkg2env

Get environment of a package.
as.list.sig

Convert to list