case: Vectorized ifelse with multiple conditions

In gmonette/spida2: Collection of tools developed for the Summer Programme in Data Analysis 2000-2012

Vectorized ifelse with multiple conditions

Description

Avoids nested ifelse statements when the action depends on the value of a variable

Usage

case(.select., ...)

Arguments

.select.	a variable whose values determine the argument to be used
...	named arguments and one possibly unnamed argument.

Details

Each argument in ... evaluates to a vector whose value is returned where the name of the argument matches a value of .select..

The vectors in ... are combined into a matrix with cbind and the names of the arguments are used as values of .select. to select which vector value is returned. See the examples.

If there is an unnamed argument, its value is used as a value in .select. is not matched by an argument name.

See an alternative: case_when

Examples

x <- c(letters[1:4],NA)
case(x, a = 'was an a', b = 'was a b', z = 'was a z')
case(x, a = 'was an a', x) # x is returned as default
# numerical 'select' is coerced to character
case(1:4, '1' = 'was a 1', '2' = 'was a 2')

location <- c('England','England','France','France',
     'Germany','Spain')
xvar <- c('yes','no','non','oui','nein','si')
case(location,
   'England' = tr(xvar, c('yes','no'), c(1,0)),
   'France'  = tr(xvar, c('oui','non'), c(1,0)),
   'Germany' = tr(xvar, c('nein','ja'), c(0,1)))
case(location,
   'England' = tr(xvar, c('yes','no'), c(1,0)),
   'France'  = tr(xvar, c('oui','non'), c(1,0)),
   'Germany' = tr(xvar, c('nein','ja'), c(0,1)),
   xvar) 
case(location,
   'England' = tr(xvar, c('yes','no'), c(1,0)),
   'France'  = tr(xvar, c('oui','non'), c(1,0)),
   'Germany' = tr(xvar, c('nein','ja'), c(0,1)),
   'no match')

gmonette/spida2 documentation built on Aug. 11, 2024, 7:52 p.m.