CODEWITHSUNDEEP
rmatrixrcpp
Anthony
Anthony

Reputation: 105

Write an Rcpp function to detect if a NumericMatrix has any NA values

I want to write an Rcpp function with a NumericMatrix argument. It returns true if any of the matrix elements are NA, false otherwise. I tried looping is_na over all the columns but I am looking for a neater way. I am also concerned about speed. 

bool check(NumericMatrix M){
n=M.ncol();
  for(int i=0; i < n; i ++){
  if(is_na( M(_,i) ){ return T;}
  } 
  return F;
}

Upvotes: 1

Views: 235

Answers (1)

coatless
coatless

Reputation: 20746

Rcpp sugar can replicate the operation by combining is_na() and any(). is_na() will detect missing values and any() verifies a single value is TRUE. Note, to retrieve a boolean value, any() must be used with is_true().

#include<Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
bool contains_na(NumericMatrix M){
  return is_true(any(is_na(M)));
}

Test case:

A = matrix(1:4, nrow = 2)
contains_na(A)
# [1] FALSE

M = matrix(c(1, 2, NA, 4), nrow = 2)
contains_na(M)
# [1] TRUE

Upvotes: 5

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