In answer to a question on R-help John Fox provided an elegant R function to translate integers into English numbers. The present package extends this code to an S3 class, with constructor functions and methods to make this original idea more conveniently available.
The function as.english is intended to provide a parallel
facility to the function as.roman in the utils package.
The main purpose of the package is to present an interesting programming example rather than to solve a likely real problem, though there could well be some applications in unusual contexts.
Note added in Version 1.1-4. The two small helper functions words
and Words are included to facilitate inline code inserts in
R markdown files. See the help files for examples. The ordinal
function produces character strings and may be used directly in inline
code inserts. Use
`r words(103)`
rather than
`r english(103)`
in R markdown files.
Note added in Version 1.2-0. The function indefinite added for
algorithmically including an apprporiate indefinite article in a
document insert. Based on a suggestion of Anne Pier Salverda.
The capitalised version, Indefinite, was added in 1.2-1.
This vignette was added in 1.2-2.
The main use envisaged for these tools is for code inserts in either R markdown or R noweb documents. It is easier here to demonstrate their function in plain code chunks, as below.
The resolution of an integer into words depends on the style of English
chosen. English (UK) style inserts the conjunction and in various places
where American (USA) style omits it. Wheter or not this happens is
governed by the english.UK option, (a logical variable, TRUE for UK
English), but if this option is unset, a guess is made as to which style
is needed depending on the user's locale.
soldiers <- 10006
oldOpt <- options(english.UK = TRUE)
cat("The Duke of York had approximately", words(soldiers), "men.\n")
cat("How many did you say? ", Words(soldiers), ", approximately.\n", sep = "")
The Duke of York had approximately ten thousand and six men.
How many did you say? Ten thousand and six, approximately.
options(english.UK = FALSE)
cat("The Duke of York had approximately", words(soldiers), "men.\n")
cat("How many did you say? ", Words(soldiers), ", approximately.\n", sep = "")
options(oldOpt)
The Duke of York had approximately ten thousand six men.
How many did you say? Ten thousand six, approximately.
Ordinal numbers are handled as well.
days <- 1:6
cat(paste("\nOn the", ordinal(days), "day of Christmas..."))
On the first day of Christmas...
On the second day of Christmas...
On the third day of Christmas...
On the fourth day of Christmas...
On the fifth day of Christmas...
On the sixth day of Christmas...
The indefinite article, “a” or “an”, can be algorithmically chosen and prepended, either in lower case or capitalised:
steps <- 7:11
cat(paste0("\nThis is ", indefinite(steps), "-step process..."))
This is a seven-step process...
This is an eight-step process...
This is a nine-step process...
This is a ten-step process...
This is an eleven-step process...
cat(paste0("\nThis is ", indefinite(steps, words = FALSE), "-step process..."))
This is a 7-step process...
This is an 8-step process...
This is a 9-step process...
This is a 10-step process...
This is an 11-step process...
cat(paste0("\n", Indefinite(ordinal(steps)), " step of the process is..."))
A seventh step of the process is...
An eighth step of the process is...
A ninth step of the process is...
A tenth step of the process is...
An eleventh step of the process is...
Roman notation is provided by the utils::as.roman function in a similar way:
numbers <- c(1:10, 1999, 2019)
punct <- c(rep(",", 10), " and",".")
cat(c("In Roman notation:",
paste0("\n\t", Words(numbers), " is written as \"",
utils::as.roman(numbers),"\"", punct)))
cat("\nDoing arithmetic in Roman notation can be difficult.")
In Roman notation:
One is written as "I",
Two is written as "II",
Three is written as "III",
Four is written as "IV",
Five is written as "V",
Six is written as "VI",
Seven is written as "VII",
Eight is written as "VIII",
Nine is written as "IX",
Ten is written as "X",
One thousand nine hundred and ninety-nine is written as "MCMXCIX" and
Two thousand and nineteen is written as "MMXIX".
Doing arithmetic in Roman notation can be difficult.
Some arithmetic operations are allowed for english objects, but to make
sense the result should be in whole numbers.
english(100) + (-5):5
[1] ninety-five ninety-six ninety-seven
[4] ninety-eight ninety-nine one hundred
[7] one hundred and one one hundred and two one hundred and three
[10] one hundred and four one hundred and five