From vandita at iirs.gov.in  Fri Aug 26 14:44:50 2011
From: vandita at iirs.gov.in (Vandita Srivastava)
Date: Fri, 26 Aug 2011 19:14:50 +0630
Subject: [Rd] Problem in calling R functions from Matlab
Message-ID: <20110826124450.M4165@iirs.gov.in>

Hi,

I wish to use R (version 2.13.1)?from within Matlab(ver R2009a) on windows XP plaform (on both 64 bit and 32 bit OS) . For this I have installed StatConnector (http://rcom.univie.ac.at/download/current/statconnDCOM.latest.exe) for calling R from within Matlab (R2009a) on Windows XP platform. I have added all the files of MATLAB_RLINK folder (downloaded from http://www.mathworks.com/matlabcentral/fileexchange/5051) into the default?Matlab working path?(D:\User\MATLAB) and also added the folder MATLAB_RLINK to the matlab path C:\Program Files\MATLAB\R2009a\toolbox . It seems that Matlab is able to connect to R however I am facing a problem while trying to call R functions from within Matlab. I have loaded all required libraries. Shown below is the sequence of commands tried in blue, outcomes in black and errors/unexpected/ undesired outcomes in red colour, and my comments in black,italic ?after the command:

>> [a b c] = openR

a =???? 1

b =???? ''

c =???? COM.StatConnectorSrv_StatConnector

>> Rdemo

b =???? 1???? 4???? 9??? 16??? 25??? 36??? 49??? 64??? 81?? 100

c =???? 2???? 5??? 10??? 17??? 26??? 37??? 50??? 65??? 82?? 101

I then tried running the Rdemo available on http://www.mathworks.com/matlabcentral/fx_files/5051/1/content/Rdemo.html

evalR('demo("persp")') works well. Also the arithmetic functions all work well:

a = 1:10;

putRdata('a',a)

b = evalR('a^2')

evalR('b <- a^2');

evalR('c <- b + 1');

c = getRdata('c')

However ?Now copy the volcano data into MATLAB? section and all related sessions therefore don?t work.

>> volcano = getRdata('volcano')

volcano =???? []

>> size(volcano)

ans =???? 0???? 0

>> surf(volcano);

(see the attached figure:surf_volcano_output.jpg)

It seems Matlab is able to read/get data from R. Other subsequent commands related to this section don?t work.

I tried looking at the loaded libraries in R and in Matlab. In R everything works well, but doesn?t seem to be so in Matlab:

>> [a b c] = evalR('.libPaths()')

a = C:/Program Files/R/R-2.13.1/library

b =???? 1

c = ?????''

>> [a b c] = evalR('library()')

a = ??'ActiveX VT_ERROR: '

??? 'base'

??? 'ActiveX VT_ERROR: '

b =???? 1

c =???? ''

>> [a b c] = evalR('library(rgdal)')

a = 'rscproxy'

??? 'lattice'

??? 'fields'

??? 'spam'

??? 'rgdal'

??? 'sp'

??? 'stats'

??? 'graphics'

??? 'grDevices'

??? 'utils'

??? 'datasets'

??? 'methods'

??? 'base'

b =???? 1

c =???? ''

As it shows that rgdal library is loaded, also the rscproxy library is loaded, in addition to all others. I tried following:

imshow(imread('testimg_p.tif')) displays the image properly, however calling this from R using rgdal from within Matlab gives error;

>> [a b c] = evalR('img <- readGDAL("testimg_p.tif")')

a = ?????[]

b = ?????0

c = Invoke Error, Dispatch Exception: Object is static; operation not allowed

The command works from R prompt:

> img <- readGDAL("testimg_p.tif") 
testimg_p.tif has GDAL driver GTiff 
and has 280 rows and 272 columns

It is giving same error while loading gstat library:

>> [a b c] = evalR('library(gstat) ')

a =???? []

b =???? 0

c = Invoke Error, Dispatch Exception: Object is static; operation not allowed

I guess the error is not related to readGDAL or gstat library but something else which I am unable to trace. I have also tried to explore if this is problem related to version of Matlab/windows 64/32 bit or R version but even that does not seem to be an issue. (I have tried this on two differemt machines one Workstation with?WinXP 64 bit OS?with R version 2.13.1and Matlab Version 7.8.0 R2009a and also?on another?portable workstation with?WinXP 32 bit?OS with R version 2.12.1 and Matlab Version 7.8.0 R2009a. This indicates that version of R or Matlab or win version 64 bit/32 bit does not seem to be an issue.

I also checked for some solution on page http://www.mathworks.com/matlabcentral/fileexchange/5051 where others also faced somewhat similar problem and it was suggested to check for setting R_HOME and PATH variables in the environment variables for your system. I understand I had followed all instructions carefully and hopefully all paths/R_HOME were set correctly, as the command evalR('.libPaths()') recognized R home path correctly. ?

I request R team to help.

Vandita Srivastava 
Scientist/Engineer "SE", 
Indian Institute of Remote Sensing(NRSC), 
ISRO/Department of Space, Govt. of India

>>Please don't print this Email unless you really need to - this will preserve trees 
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[Rd] Problem in calling R functions from Matlab
Vandita Srivastava