ifelse {base}
Description
ifelse returns a value with the same shape as test which is filled with elements selected from either yes or no depending on whether the element of test is TRUE or FALSE.
Usage
ifelse(test, yes, no)
Arguments
- test
- an object which can be coerced to logical mode.
- yes
- return values for true elements of
test. - no
- return values for false elements of
test.
Details
If yes or no are too short, their elements are recycled. yes will be evaluated if and only if any element of test is true, and analogously for no.
Missing values in test give missing values in the result.
Values
A vector of the same length and attributes (including dimensions and "class") as test and data values from the values of yes or no. The mode of the answer will be coerced from logical to accommodate first any values taken from yes and then any values taken from no.
Warning
The mode of the result may depend on the value of test (see the examples), and the class attribute (see oldClass) of the result is taken from test and may be inappropriate for the values selected from yes and no.
Sometimes it is better to use a construction such as
(tmp <- yes; tmp[!test] <- no[!test]; tmp)
, possibly extended to handle missing values in test.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
if.
Examples
x <- c(6:-4) sqrt(x) #- gives warning sqrt(ifelse(x >= 0, x, NA)) # no warning ## Note: the following also gives the warning ! ifelse(x >= 0, sqrt(x), NA) ## example of different return modes: yes <- 1:3 no <- pi^(0:3) typeof(ifelse(NA, yes, no)) # logical typeof(ifelse(TRUE, yes, no)) # integer typeof(ifelse(FALSE, yes, no)) # double
Documentation reproduced from R 3.0.1. License: GPL-2.