Execute R script from PHP with Apache Server - php

Question

I want to execute a R script (named script.R) within PHP code with an Apache Web Server.
Here is my R code : I install packages then import data then I can proceed a classification tree on the data:
library(lubridate)
library(plyr)
library(rpart)
library(sqldf)
library(survival)
library(randomForest)
library(rpart.plot)
data=read.table(file = "t.txt",header = T,sep = ";",stringsAsFactors = T)
input=read.table(file = "file.txt",header = T,sep = ";",stringsAsFactors = T)
tree=rpart(sat~.,data,method="class")
png("tree.png", width=1000, height=800, antialias="cleartype")
plot(tree, uniform=TRUE,
main="Classification Tree")
text(tree, use.n=TRUE, all=TRUE, cex=0.8)
dev.off()
My php script must execute this R script. They are placed in "C:\Apache24\htdocs" with "file.txt" and "t.txt"
So my php file consists in :
<?php
exec("Rscript script.R", $results);
print_r($results);
?>
But I get "Array()"
Any idea?

Answer 1

Install required R packages in system-wide location. On my machine this requires:
$ sudo R
> install.packages("Rpkg", lib = "/usr/local/lib/R/site-library/")
Explanation:
I see you have installed couple of R packages. And I'm guessing that you have installed them in default location i.e. user home directory.
So if you try to execute your R script from command-line, something like:
$ php foo.php
You'll see that the script gets executed successfully (assuming rest of the code is bug free) and the script.R gets called as expected.
But this will fail when you try to execute php from apache. The reason is that since you have installed R packages in home directory they are inaccessible to www-data, the user which executes php under apache.