s: Simple expression substitution

Description

Evaluate R expressions and substitute their values into a string.

Usage

s(string, round = NULL, signif = NULL, envir = parent.frame())

Arguments

string

The string to substitute into, containing any number of "#{}" blocks.

round

NULL or a single integer, giving the number of decimal digits for rounding numeric expressions. This argument takes priority over signif.

signif

NULL or a single integer, giving the number of significant decimal digits to use for numeric expressions. The round argument takes priority over this one and will be used if not NULL.

envir

The environment to evaluate expressions in.

Value

The final string, with expressions substituted into it.

Details

Each part of the string surrounded by "#{}" is extracted, evaluated as R code in the specified environment, and then its value is substituted back into the string. The literal string "#{}" can be obtained by escaping the hash character, viz. "\\#{}". The block may contain multiple R expressions, separated by semicolons, but may not contain additional braces. If the reportrNumericRepresentation option is defined and is a list, its round and signif elements provide defaults for the arguments of the same name.

Examples

Run this code

s("pi is #{pi}")
s("pi is \\#{pi}")
s("The square-root of pi is approximately #{sqrt(pi)}", signif=4)
s("1/(1+x) for x=3 is #{x <- 3; 1/(1+x)}")