GitHub - jamesdunham/concatenate: Human-friendly text from unknown values in R (original) (raw)

Functions in concatenate construct human-friendly text from elements whose values aren't known in advance, as in calls to message, warning or stop.

Basics

Each function in concatenate returns a comma-separated string. (A length-one character vector.) The workhorse function in concatenate is cc.

cc("one fish", "two fish") #> [1] "one fish, two fish"

Its wrappers cc_or and cc_and insert "or" and "and" between the last two elements of the input. This is cleaner than wrestling with paste.

cc_and("this", "that", "the other") #> [1] "this, that and the other" cc_or("one way", "another") #> [1] "one way or another"

cn and its derivatives combine these functions with sprintf-like substitution and the grammatical number awareness of ngettext.

Like ngettext, the cn functions return different strings depending on the number of the object, and two substitutions are made sprintf-style:

• "%c": the comma-concatenated values of the object, as in cc
• "%n": the number of the object

This encourages verbose user-facing messages from clean code.

x <- unique(iris$Species) cn_and(x, "a single species: %c", "%n unique species: %c") #> [1] "3 unique species: setosa, versicolor and virginica"

There are row-wise data.frame methods for the cn functions.

singular <- "%n row: %c" plural <- "%n rows whose values are %c" cn(chickwts[1, ], singular, plural) #> [1] "1 row: 179, horsebean" cn_and(chickwts[1:3, 1, drop = FALSE], singular, plural) #> [1] "3 rows whose values are 179, 160 and 136"

The cc functions are also available as binary infix operators.

x <- "important value" x %c% "!" #> [1] "important value!"

Install

concatenate is available via CRAN.

install.packages("concatenate")

Or, get it from GitHub.

devtools::install_github("jamesdunham/concatenate")