R.utils (version 2.9.0)

GString: Character string with advanced substitutions

Description

Package: R.utils Class GString

character ~~| ~~+--GString

Directly known subclasses:

public static class GString extends character

Usage

GString(..., sep="")

Arguments

...

one or more objects, to be coerced to character vectors.

sep

A character string to separate the terms.

Fields and Methods

Methods:

	as.character	Gets the processed character string.
	evaluate	Parses and evaluates a GString.
	gcat	-
	getBuiltinDate	Gets the current date.
	getBuiltinDatetime	Gets the current date and time.
	getBuiltinHostname	Gets the hostname of the system running R.
	getBuiltinOs	Gets the operating system of the running machine.
	getBuiltinPid	Gets the process id of the current R session.
	getBuiltinRhome	Gets the path where R is installed.
	getBuiltinRversion	Gets the current R version.
	getBuiltinTime	Gets the current time.
	getBuiltinUsername	Gets the username of the user running R.
	getRaw	Gets the unprocessed GString.
	getVariableValue	Gets a variable value given a name and attributes.
	gstring	-
	parse	Parses a GString.
	print	Prints the processed GString.

Methods inherited from character: Ops,nonStructure,vector-method, Ops,structure,vector-method, Ops,vector,nonStructure-method, Ops,vector,structure-method, all.equal, as.Date, as.POSIXlt, as.data.frame, as.raster, coerce,ANY,character-method, coerce,character,SuperClassMethod-method, coerce,character,signature-method, coerce<-,ObjectsWithPackage,character-method, coerce<-,signature,character-method, downloadFile, formula, getDLLRegisteredRoutines, isOpen, toAsciiRegExprPattern, toFileListTree, uses

See Also

For convenience, see functions gstring() and gcat().

Examples

# NOT RUN {
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# First example
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
who <- "world"

# Compare this...
cat(as.character(GString("Hello ${who}\n")))

# ...to this.
cat(GString("Hello ${who}\n"))

# Escaping
cat(as.character(GString("Hello \\${who}\n")))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Looping over vectors
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
x <- 1:5
y <- c("hello", "world")
cat(as.character(GString("(x,y)=(${x},${y})")), sep=", ")
cat("\n")

cat(as.character(GString("(x,y)=(${x},$[capitalize]{y})")), sep=", ")
cat("\n")


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Predefined ("builtin") variables
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
cat(as.character(GString("Hello ${username} on host ${hostname} running ",
"R v${rversion} in process #${pid} on ${os}. R is installed in ${rhome}.")))


# Other built-in variables/functions...
cat(as.character(GString("Current date: ${date}\n")))
cat(as.character(GString("Current date: $[format='%d/%m/%y']{date}\n")))
cat(as.character(GString("Current time: ${time}\n")))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Evaluating inline R code
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
cat(as.character(GString("Simple calculation: 1+1=${`1+1`}\n")))
cat(as.character(GString("Alternative current date: ${`date()`}\n")))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Function values
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Call function rnorm with arguments n=1, i.e. rnorm(n=1)
cat(as.character(GString("Random normal number: $[n=1]{rnorm}\n")))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Global search-replace feature
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Replace all '-' with '.'
cat(as.character(GString("Current date: ${date/-/.}\n")))
# Another example
cat(as.character(GString("Escaped string: 12*12=${`12*12`/1/}\n")))


# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Defining new "builtin" function values
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Define your own builtin variables (functions)
setMethodS3("getBuiltinAletter", "GString", function(object, ...) {
  base::letters[runif(1, min=1, max=length(base::letters))]
})

cat(as.character(GString("A letter: ${aletter}\n")))
cat(as.character(GString("Another letter: ${aletter}\n")))


# Another example
setMethodS3("getBuiltinGstring", "GString", function(object, ...) {
  # Return another GString.
  GString("${date} ${time}")
})

cat(as.character(GString("Advanced example: ${gstring}\n")))


# Advanced example
setMethodS3("getBuiltinRunif", "GString", function(object, n=1, min=0, max=1, ...) {
  formatC(runif(n=n, min=min, max=max), ...)
})

cat(as.character(GString("A random number: ${runif}\n")))
n <- 5
cat(as.character(GString("${n} random numbers: ")))
cat(as.character(GString("$[n=n, format='f']{runif}")))
cat("\n")


# Advanced options.
# Options are parsed as if they are elements in a list, e.g.
#   list(n=runif(n=1,min=1,max=5), format='f')
cat(as.character(GString("$Random number of numbers: ")))
cat(as.character(GString("$[n=runif(n=1,min=1,max=5), format='f']{runif}")))
cat("\n")
# }