Find Rows/Columns Using a Predicate

Finds rows/columns in an array-like object using a predicate function.

Usage

detect(x, ...)

# S4 method for class 'ANY'
detect(x, f, margin = 1, negate = FALSE, all = FALSE, na.rm = FALSE, ...)

Arguments

x

An R object (should be a matrix or a data.frame).

...

Further arguments to be passed to f.

f

A predicate function.

margin

A length-one numeric vector giving the subscripts which the function will be applied over (1 indicates rows, 2 indicates columns).

negate

A logical scalar: should the negation of f be used instead of f?

all

A logical scalar. If TRUE, only the rows/columns whose values all meet the condition defined by f are considered. If FALSE (the default), only rows/columns where at least one value validates the condition defined by f are considered.

na.rm

A logical scalar: should NA values be stripped before the computation proceeds?

Value

A logical vector.

See also

Other data preparation tools: append_column(), append_rownames(), assign(), compact(), count(), discard(), get(), keep(), seek()

Author

N. Frerebeau

Examples

## Create a data matrix
X <- matrix(sample(1:10, 25, TRUE), nrow = 5, ncol = 5)

## Add NA
k <- sample(1:25, 3, FALSE)
X[k] <- NA
X
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    8    9    8   NA    7
#> [2,]    6    8    8    7   10
#> [3,]   10    2    3   NA   10
#> [4,]    1    7   NA   10    3
#> [5,]    8    1    2    3    1

## Find row with NA
detect(X, f = is.na, margin = 1)
#> [1]  TRUE FALSE  TRUE  TRUE FALSE
## Find column without any NA
detect(X, f = is.na, margin = 2, negate = TRUE, all = TRUE)
#> [1]  TRUE  TRUE FALSE FALSE  TRUE