CODEWITHSUNDEEP
rrcpp
S.Shen
S.Shen

Reputation: 23

r aborted when using rcpp

I am writing some code, and when running, it aborted. The r version is 3.5.1. I think there is something wrong with my rcpp code, but I can't find it. It just shows R session aborted.

################I don't think there is anything wrong in this part. 
#include <Rcpp.h>

Rcpp::LogicalVector logical_index(Rcpp::IntegerVector idx, R_xlen_t n) {
  bool invert = false; 
  Rcpp::LogicalVector result(n, false);

  for (R_xlen_t i = 0; i < idx.size(); i++) {
    if (!invert && idx[i] < 0) invert = true;
    result[std::abs(idx[i])] = true;
  }

  if (!invert) return result;
  return !result;
}


// [[Rcpp::export]]
Rcpp::NumericVector 
  Subset(Rcpp::NumericVector x, Rcpp::IntegerVector idx) {
    return x[logical_index(idx, x.size())];
  }
# ################There maybe something wrong in this part. 
library(Rcpp)
library(gRbase)
vec=0:13
a=combnPrim(vec,4)
cppFunction("
NumericVector r_test(NumericMatrix a, Function comp, Function fct,Function 
tempf, Function combnPrim, NumericVector Fv, NumericVector vec, Function 
Subset){
        NumericVector if1(4);
        NumericVector if2(2);
        NumericVector if3(4);
        NumericVector if4(4);
        NumericVector seq(14);
        NumericMatrix b(2,45);
        NumericMatrix c(4,70);
        for (int i1=0; i1<=a.ncol()-1; i1++){
        if1=a (_, i1);
        b=combnPrim(Subset(vec,-(if1)),2);
        for (int i2=0; i2<=b.ncol()-1; i2++){
        if2=b (_, i2);
        c=combnPrim(Subset(Subset(vec,-(if1)),-(if2)),4);
        for (int i3=0; i3<=c.ncol()-1; i3++){
        if3=c (_, i3);
        if4=Subset(Subset(Subset(vec,-(if1)),-(if2)),-(if3));
        seq=tempf(if1,if2,if3,if4);
        }}}return if1;}")

Fv=7.001327
setwd("D:/STAT 602")

sourceCpp("Subset.cpp")

fct=function(seq,data,fact){
  return(anova(lm(data[seq]~as.factor(fact)))$`F value`[1])
}
tempf=function(x1,x2,x3,x4){
  return(c(x1,x2,x3,x4))
}
comp=function(x,y){
  return(x>y)
}
r_test(a,comp, fct, tempf, combnPrim, Fv, vec, Subset)
#

combnPrim is used to find all combination of a vector, and it outputs a matrix, and Subset is the same use as vector[-i]. Individually, all function can act well in cppFunction, but when putting them like this, things go wrong.

Upvotes: 1

Views: 649

Answers (1)

duckmayr
duckmayr

Reputation: 16920

Since this code is pretty convoluted, I'm not going to hunt for the exact, specific bug. However, I can confirm that @RalfStubner was right that your problem is that you're trying to access an element of a vector that does not exist.

If you change logical_index() to 

LogicalVector logical_index(IntegerVector idx, R_xlen_t n) {
    bool invert = false;
    LogicalVector result(n, false);

    for (R_xlen_t i = 0; i < idx.size(); i++) {
        if (!invert && idx(i) < 0) invert = true;
        result(std::abs(idx(i))) = true;
    }

    if (!invert) return result;
    return !result;
}

so that element access is done via () rather than [] to ensure bounds checking,1 rather than just aborting, I see the following:

r_test(a,comp, fct, tempf, combnPrim, Fv, vec, Subset)

Error in r_test(a, comp, fct, tempf, combnPrim, Fv, vec, Subset) :
Evaluation error: Index out of bounds: [index=10; extent=8]..

This means you're trying to access an element of a vector that does not exist. I can also tell you the basic reason why this is happening: In logical_vector(), when an element of idx is greater than n, this will occur. So, at some point in r_test(), you are calling Subset() with idx that has an element greater than x.size().

1 You are right that you'll get an error trying to use () for vector subsetting when subsetting a vector by another vector. However, this works when accessing one element of a vector.

Upvotes: 2

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