Apply a predicate function over a list or vector

Returns a logical of the same length as X, each element of which is the result of applying predicate FUN to the corresponding element of X.

Usage

predapply(X, FUN, ..., reduce = NULL, na.as = NA)

Arguments

X

a vector (atomic or list) or an expression object. Other objects (including classed objects) will be coerced by as.list.

FUN

a predicate function to be applied to each element of X that returns a single logical value.

...

optional arguments to FUN.

reduce

NULL or one of "all", "any", or "none". When non-NULL, the output logical vector is reduced to a single boolean value using all, any or "none" (implemented as all(!logi)).

na.as

logical value to return for NA values in the output logical vector (NA, TRUE or FALSE).

Value

logical vector or boolean if reduce is non-NULL.

Details

na.as is most meaningful when reduce is non-NULL, as it allows control flow calls (e.g., if (predapply(...))) to proceed without error. See examples.

See also

apply, lapply, mapply, all, any.

Examples

x <- list(a = 1, b = 2, c = NA)
predapply(x, is.numeric)
#>     a     b     c 
#>  TRUE  TRUE FALSE 
predapply(x, is.numeric, reduce = "any")
#> [1] TRUE

x <- list(a = 1, b = 2, c = 3)
predapply(x, is.numeric, reduce = "all")
#> [1] TRUE

x <- list(a = "1", b = "2", c = "3")
predapply(x, is.numeric, reduce = "none")
#> [1] TRUE

x <- c(1, 2, NA)
predapply(x, function(x) x > 0)
#> [1] TRUE TRUE   NA
predapply(x, function(x) x > 0, reduce = "all")
#> [1] NA
predapply(x, function(x) x > 0, reduce = "all", na.as = TRUE)
#> [1] TRUE