R: Conditional Element Selection

ifelse {base} | R Documentation

## Conditional Element Selection

### 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`. If `yes` or `no` are too short, their elements are recycled.

### Usage

    ifelse(test, yes, no)

### Arguments

`test` | a logical vector
`yes` | return values for true elements of `test`.
`no` | return values for false elements of `test`.

### 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)

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