How to check a data.frame for any non-finite

Question

I\'d like to check if a data.frame has any non-finite elements.

This seems to evaluate each column, returning FALSE for each (I\'m guessing its evaluating the data.f

Answer 1

Your solution of calling as.matrix will only work if the data.frame only has numeric columns. Otherwise, the matrix will typically become a character matrix and the result will be false everywhere...

@joran has a good approach, but you'll have problems with factor columns unless to add a method for factors too etc...

is.finite(letters[1:3])         # FALSE - OK
is.finite(factor(letters[1:3])) # TRUE - WRONG!!

is.finite.factor <- function(obj){
    logical(length(obj))
}

is.finite(factor(letters[1:3])) # FALSE - OK

Also, if you want the check to be as fast as possible, you should avoid sapply and go for vapply instead.

d <- data.frame(matrix(runif(1e6), nrow=10), letters[1:10])

# @joran's method
is.finite.data.frame <- function(obj){
    sapply(obj,FUN = function(x) all(is.finite(x)))
}

system.time( x <- is.finite(d) ) # 0.42 secs

# Using vapply instead...
is.finite.data.frame <- function(obj) {
    vapply(obj,FUN = function(x) all(is.finite(x)), logical(1))
}

system.time( y <- is.finite(d) ) # 0.20 secs

identical(x,y) # TRUE