[Rd] Problem in calling R functions from Matlab

[Vandita Srivastava]

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

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