I need to plot 2D histograms of four columns of datasets in a data file.
here is my code:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include "TFile.h"
#include "TGraphErrors.h"
#include "TH2.h"
using namespace std;
int main() {
// reading an ascii file
int row = 0;
double my_array[1839][4];
ifstream myfile ("test.txt");
if ( myfile.is_open() ) {
string line;
while( getline(myfile,line)) {
cout << line << endl;
stringstream ss(line);
int col=0;
while (ss >> my_array[row][col]) col++;
row++;
}
}
myfile.close();
for (int i=0; i <1839; ++i) {
cout << "my_array " << my_array[i][0] << ", " << my_array[i][1] << "," << m\
y_array[i][2] << my_array[i][3] << endl;
}
TH2D *hitm = new TH2D("hitm","hitmap", 256,-0.5,255.5,256,-0.5,255.5);
for (int i=0; i <1839; ++i) {
double x = my_array[i][0];
double y = my_array[i][1];
double z = my_array[i][2];
double d = my_array[i][3];
return 0;
}
'
it doesn't work yet, all of what it do is printing the columns on the terminal, can you please help me on that ?
thanks in advance
Related
//How do I count numbers in the input vector that is greater and lesser than input number X?
#include <iostream>
#include
#include
using namespace std;
int main()
{
int i, size;
float verdi = 0;
vector<float> minvektor;
cout << "input vectorsize " << endl;
cin >> size;
cout << "Input vector-numbers, use enten space or enter to space/divide numbers. " << endl;
for (i = 0; i < size; i++)
{
cin >> verdi;
minvektor.push_back(verdi);
}
for (i = 0; i < size; i++)
{
cout << minvektor[i] << " ";
}
// -------------------------------------------------
cout << "\ninput number X to compare to vector: " << endl;
float X;
cin >> X;
//count numbers in a vector that is greater than X
//output ex: 5 numbers in a vector that is greater than number X
}
in an R script I source a cpp file to make some calculations. In that R script, a function defined in the cpp file is called and a matrix and an integer is provided. After a few rounds through the loop it gives the error "Not a matrix" (in line of code resid = (x(_,j) - x(_,i))*(x(_,j) - x(_,i));), even though for the rounds before it worked.
R script:
## all together
# rm(list=ls())
library(RcppArmadillo)
library(Rcpp)
sourceCpp("~/test.cpp",verbose = FALSE)
cat("start loop")
for(n in c(45:46)){
cat("\n", n, "\n")
p_m <- matrix(data=rnorm(n^2,1,1),nrow = n, ncol=n)
print(class(p_m))
print(some_function(p_m,nosamples=10))
}
cat("finished")
I start this R script via the command line. R version R-4.1.0. In R-Studio it crashes with a fatal error.
The cpp file:
// [[Rcpp::depends(RcppArmadillo)]]
#include <RcppArmadillo.h>
using namespace Rcpp;
// [[Rcpp::export]]
NumericVector some_function(NumericMatrix x,int nosamples) {
int ncol = x.ncol();
NumericVector out2(nosamples);
int loops;
int loops2;
double result=0;
NumericVector::iterator it;
double acc = 0;
NumericVector resid(ncol);
NumericVector out(ncol*(ncol-1)/2);
loops2=0;
std::cout << nosamples << std::endl;
std::cout << (ncol-1) << std::endl;
std::cout << ncol*(ncol-1)/2 << std::endl;
while(loops2 < (nosamples)){
std::cout << "loops2:" << std::endl;
std::cout << loops2 << std::endl;
loops=0;
int i;
int j;
for(j=0;j<(ncol-1);++j){
std::cout << " j: " << j << std::endl;
for (i = (j+1); i < (ncol); ++i) {
std::cout << " i: " << i << std::endl;
resid = (x(_,j) - x(_,i))*(x(_,j) - x(_,i)); //here it stops
std::cout << " i: " << i << std::endl;
for(int ii=0; ii<ncol;++ii){
acc += resid[i];
}
result=sqrt(acc);
loops += 1;
out[loops] = result;
std::cout << " i: " << i << std::endl;
}
}
std::cout << "loops:" << std::endl;
std::cout << loops << std::endl;
out = out[out > 0];
it = std::min_element(out.begin(), out.end());
out= *it;
std::cout << out << std::endl;
loops2 += 1;
out2[loops2]=out[0];
}
std::cout << "cpp finished" << std::endl;
return(out2);
}
Can someone explain what the problem is about?
Thanks and kind regards
Edit
I adapted some things in the cpp file (shown below) and the error disappeared. First I thought, everything is fine. But when I increase the number of loops, another problem occurs: the function breaks, but no error is shown. It breaks after loop number 543 ("loop2: 543"). At least it does the same in each round of the while loop with the same data.
I adapted the R-script and the ccp file to make this problem (at least on my machine) reproducible.
I know this code seems to be somehow meaningless, but it is part of a bigger program and I wanted to give here a minimum example.
The R script:
## all together
# rm(list=ls())
library(RcppArmadillo)
library(Rcpp)
sourceCpp("~/test.cpp",verbose = FALSE)
cat("start loop")
for(n in c(100:101)){
cat("\n", n, "\n")
p_m <- matrix(data=rnorm(n^2,1,1),nrow = n, ncol=n)
print(class(p_m))
print(some_function(p_m,nosamples=800))
}
cat("finished")
The cpp file:
// [[Rcpp::depends(RcppArmadillo)]]
// [[Rcpp::depends(RcppEigen)]]
#include <RcppArmadillo.h>
#include <RcppEigen.h>
using namespace Rcpp;
using Eigen::Map;
using Eigen::VectorXd;
typedef Map<VectorXd> MapVecd;
// [[Rcpp::export]]
NumericVector some_function(NumericMatrix x,int nosamples) {
int ncol = x.ncol();
NumericVector out(ncol*(ncol-1)/2);
NumericVector out2(nosamples);
NumericVector out3(ncol*(ncol-1)/2);
NumericVector resid(ncol);
int loops;
int loops2;
double result=0;
double acc = 0;
int show_cout=0;
loops2=0;
std::cout << nosamples << std::endl;
std::cout << (ncol-1) << std::endl;
std::cout << ncol*(ncol-1)/2 << std::endl;
while(loops2 < (nosamples)){
std::cout << "loops2:" << loops2 << std::endl;
loops=0;
int i;
int j;
for(j=0;j<(ncol-1);++j){
// std::cout << " j: " << j << std::endl;
for (i = (j+1); i < (ncol); ++i) {
if(show_cout==1){
std::cout << " i: " << i << std::endl;
}
resid = (x(_,j) - x(_,i))*(x(_,j) - x(_,i));
if(show_cout==1){
std::cout << " i: " << i << std::endl;
}
for(int ii=0; ii<ncol;++ii){
acc += resid[ii];
}
result=sqrt(acc);
loops += 1;
out[loops] = result;
if(show_cout==1){
std::cout << " i: " << i << std::endl;
}
}
}
// std::cout << "loops:" << loops << std::endl;
//
out = out[out > 0];
const MapVecd xy(as<MapVecd>(out));
out3=xy.minCoeff();
out2[loops2]=out3[0];
loops2 += 1;
}
std::cout << "cpp finished" << std::endl;
return(out2);
}
Two things here:
Use out[loops++] = result; instead of loops += 1; out[loops] = result; because you were starting at 1, and probably accessing the last element outside of the range of this vector.
Use
for(int ii=0; ii<ncol;++ii){ double eps = x(ii, j) - x(ii, i); acc += eps * eps; }
instead of relying on this resid vector.
I need to send array pieces to all processes using MPI_Scatter then to get sum of all elements. Where should I initialize array then to scatter it? In root rank?
If I initialize array on root rank then other ranks dont get their data. Otherway I can initialize array for everyone (out of if(rank == root)...else), but it means, that I create array several times.
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
#include <iostream>
#include <time.h>
using namespace std;
int main(int argc, char* argv[])
{
int size;
int rank;
srand(time(NULL));
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
int arr_size = size * 2;
int block = arr_size / (size);
int* B = new int[block];
if (rank == 0)
{
int* A = new int[arr_size];
cout << "generated array: " << endl;
for (int i = 0; i < arr_size; i++)
{
A[i] = rand() % 100;
cout << A[i] << " ";
}
cout << endl;
MPI_Scatter(A, block, MPI_INT, B, block, MPI_INT, 0, MPI_COMM_WORLD);
}
cout << "process " << rank << " received: " << endl;
for (int i = 0; i < block; i++)
{
cout << B[i] << " ";
}
cout << endl;
int local_sum = 0;
for (int i = 0; i < block; i++)
{
local_sum += B[i];
}
cout << "sum in process " << rank << " = " << local_sum << endl;
cout << endl;
int global_sum;
MPI_Reduce(&local_sum, &global_sum, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
if (rank == 0)
{
cout << "sum = " << global_sum << endl;
}
MPI_Finalize();
return 0;
}
I get something like this (only root rank got its data):
process 1 received:
process 3 received:
-842150451 -842150451
-842150451 -842150451
sum in process 1 = -1684300902
sum in process 3 = -1684300902
process 2 received:
-842150451 -842150451
sum in process 2 = -1684300902
process 0 received:
4 9
sum in process 0 = 13
sum = -757935397
MPI_Scatter() is a collective operation and must hence be invoked by all the ranks.
Declare int *A = NULL; on all ranks and only allocate and populate on rank zero.
int* A = NULL;
int* B = new int[block];
if (rank == 0)
{
A = new int[arr_size];
cout << "generated array: " << endl;
for (int i = 0; i < arr_size; i++)
{
A[i] = rand() % 100;
cout << A[i] << " ";
}
cout << endl;
}
MPI_Scatter(A, block, MPI_INT, B, block, MPI_INT, 0, MPI_COMM_WORLD);
I made a small reproducible example:
#include <Rcpp.h>
using namespace Rcpp;
class Index {
public:
Index(int i_) : i(i_) {}
int getI() { return i; }
private:
int i;
};
// [[Rcpp::export]]
SEXP getXPtrIndex(int i) {
Rcout << "getXPtrIndex: i = " << i << std::endl;
Index ind(i);
Rcout << "getXPtrIndex: ind.i = " << ind.getI() << std::endl;
return XPtr<Index>(&ind, true);
}
// [[Rcpp::export]]
void getXPtrIndexValue(SEXP ptr) {
XPtr<Index> ind_ptr(ptr);
Rcout << "getXPtrIndexValue: ind_ptr->i = " << ind_ptr->getI() << std::endl;
Index ind = *ind_ptr;
Rcout << "getXPtrIndexValue: ind.i = " << ind.getI() << std::endl;
}
Basically, I define a small class, along with a function to get an external pointer of an element of this class. The last function is used to print the weird accessor when returning the class element back to C++.
Results in R:
> (extptr <- getXPtrIndex(10))
getXPtrIndex: i = 10
getXPtrIndex: ind.i = 10
<pointer: 0x7ffeeec31b00>
> getXPtrIndexValue(extptr)
getXPtrIndexValue: ind_ptr->i = 33696400
getXPtrIndexValue: ind.i = 0
Why can't I access 10?
I'm using Rcpp version 0.12.12 (the latest I think).
It seems to have something to do with the temporary object---by the time your second function runs the "content" of the first is already gone.
So either just make
Index ind(10);
a global, and comment out the line in your first function. Then all is peachy (I changed the R invocation slightly):
R> extptr <- getXPtrIndex(10)
getXPtrIndex: i = 10
getXPtrIndex: ind.i = 10
R> getXPtrIndexValue(extptr)
getXPtrIndexValue: ind_ptr->i = 10
getXPtrIndexValue: ind.i = 10
R>
Or it also works the same way when you make you Index object static to ensure persistence. Corrected example below.
#include <Rcpp.h>
using namespace Rcpp;
class Index {
public:
Index(int i_) : i(i_) {}
int getI() { return i; }
private:
int i;
};
// [[Rcpp::export]]
SEXP getXPtrIndex(int i) {
Rcout << "getXPtrIndex: i = " << i << std::endl;
static Index ind(i);
Rcout << "getXPtrIndex: ind.i = " << ind.getI() << std::endl;
return XPtr<Index>(&ind, true);
}
// [[Rcpp::export]]
void getXPtrIndexValue(SEXP ptr) {
XPtr<Index> ind_ptr(ptr);
Rcout << "getXPtrIndexValue: ind_ptr->i = " << ind_ptr->getI() << std::endl;
Index ind = *ind_ptr;
Rcout << "getXPtrIndexValue: ind.i = " << ind.getI() << std::endl;
}
/*** R
extptr <- getXPtrIndex(10)
getXPtrIndexValue(extptr)
*/
What is wrong with my code ? I have the error like this.
Unhandled exception at 0x00d21673 in mnozenie_macierzy.exe : 0xC0000005: Access violation writing location 0xcdcdcdcd.
It create the first array and the half to the second. The program multiplies arrays.
Sorry for my English if It isn't correct. I hope you understand me.
#include <iostream>
#include <time.h>
using namespace std;
void losowa_tablica(int **tab1, int **tab2, int a, int b, int c, int d)
{
int i, j;
for(i=0; i<a; i++)
{
cout << endl;
for(j=0; j<b; j++)
{
tab1[i][j]=rand();
cout << "tab1[" << i << "][" << j << "] : \t" << tab1[i][j] << "\t";
}
}
cout << endl;
for(i=0; i<c; i++)
{
cout << endl;
for(j=0; j<d; j++)
{
tab2[i][j]=rand();
cout << "tab2[" << i << "][" << j << "] : \t" << tab2[i][j] << "\t";
}
}
cout << endl << endl;
}
int **mnozenie(int **tab1, int **tab2, int a, int b, int c, int d)
{
int g, suma, i, j;
int **mac=new int*[a];
for(int i=0; i<d; i++)
mac[i]=new int[d];
for(i=0; i<a; i++)
for(j=0; j<d; j++)
{
g=b-1, suma=0;
do
{
suma+=tab1[i][g]*tab2[g][j];
g--;
}while(g!=0);
mac[i][j]=suma;
}
return mac;
}
int main()
{
int a,b,c,d;
cout << "Podaj liczbe wierszy pierwszej macierzy: " << endl;
cin >> a;
cout << "Podaj liczbe kolumn pierwszej macierzy: " << endl;
cin >> b;
cout << "Podaj liczbe wierszy drugiej macierzy: " << endl;
cin >> c;
cout << "Podaj liczbe kolumn drugiej macierzy: " << endl;
cin >> d;
int **tab1=new int*[a];
for(int i=0; i<b; i++)
tab1[i]=new int[b];
int **tab2=new int*[c];
for(int i=0; i<d; i++)
tab2[i]=new int[d];
losowa_tablica(tab1, tab2, a, b, c, d);
if ( b==c )
{
cout << "Mnozenie wykonalne" << endl;
int **mno=mnozenie(tab1, tab2, a, b, c, d);
}
else cout << "Mnozenie niewykonalne" << endl;
system("pause");
}
Your code yields undefined behavior:
int **tab1=new int*[a]; // allocating an array of 'a' elements
for(int i=0; i<b; i++) // if b > a then the next line will eventually yield UB
tab1[i]=new int[b];
int **tab2=new int*[c]; // allocating an array of 'c' elements
for(int i=0; i<d; i++) // if d > c then the next line will eventually yield UB
tab2[i]=new int[d];
int **mac=new int*[a]; // allocating an array of 'a' elements
for(int i=0; i<d; i++) // if d > a then the next line will eventually yield UB
mac[i]=new int[d];
In practice, the above code will most likely perform a memory access violation at some point.