1. C call R Using .R file in C
T. B. Chen in NCTU
2019/5/29

2. Why Using “BATCH” file runs R functions.
Fast : Without using R’s GUI.
Easy : Only including a .R file in C.
Combination advantages of R and C.
Avoid looping control in R.
Text file, I/O in C, could share with R.
Easy handling user’s sub-routines.
2019/5/29

3. Principle R GUI Packages .R File DLL I/O Text File .c File
System library
User’s library
External library
2019/5/29

4. .R File Simulation a model using R. Codes
Y = u + Bx + error, error~N(0,1)
Codes
u = 10;
B=3.5;
N=10000;
error=rnorm(N);
x=rpois(N,10);
Y=u+B*x+error
Xx=cbind(x,Y)
write.csv(Xx, file='d:/XYdata.txt‘,row.names = FALSE)
2019/5/29

5. .C File Using .R Codes: #include <stdio.h>
#include <stdlib.h>
FILE *in;
void main(){
Expr……….
system(“C:/progra~1/R/R-2.3.1/bin/R CMD BATCH D:/RunR/Test.R”);
in = fopen(“d:/XYdata.txt”,”r”);
fclose(in); }
2019/5/29

6. .C File Using .R (2) Codes: #include <stdio.h>
#include <stdlib.h>
FILE *in, *out;
void main(int argc, char** argv){
Expr……….
out = fopen(“d:/Runr/Ch14.R”,”w”);
fprintf(out,” error=rnorm(%d)\n”,N);
………………………
fprintf(out,” write.csv(Xx, file=‘%s', row.names = FALSE)\n”,argv[1]);
fclose(out);
system(“C:/progra~1/R/R-2.3.1/bin/R CMD BATCH D:/RunR/Ch14.R”);
in = fopen(“d:/XYdata.txt”,”r”);
fclose(in); }
2019/5/29