How to find out which package version is loaded in R?

Question

I am in a process of figuring out how to use my university cluster. It has 2 versions of R installed. System wide R 2.11 (Debian 6.0) and R 2.14.2 in non-standard location.

I am trying to use MPI together with snow. The code I am trying to run is the following

library(snow)
library(Rmpi)
cl <- makeMPIcluster(mpi.universe.size()-1)
stopCluster(cl)
mpi.quit()

It works without the problems on R 2.11. (I launch the script with mpirun -H localhost,n1,n2,n3,n4 -n 1 R --slave -f code.R). Now when I try to do it with R 2.14.2, I get the following message:

Error: This is R 2.11.1, package 'snow' needs >= 2.12.1
In addition: Warning message:

So it seems that R loads the package snow version compiled for R 2.11. I've installed snow under R 2.14 into my home folder and I added the following lines to my code:

.libPaths("/soft/R/lib/R/library")
.libPaths("~/R/x86_64-pc-linux-gnu-library/2.11")
print(.libPaths())
print(sessionInfo())
print(version)

And the output before the error confirms that I am indeed running R 2.14.2 and my R packages folder is first in search path. But I still get the error.

So my question is how do I determine which version of package is loaded in R? I can see with installed.packages all the packages which are installed, so maybe there is some function which lists similar information for loaded packages?

Answer 1

You can use sessionInfo() to accomplish that.

> sessionInfo()
R version 2.15.0 (2012-03-30)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=C                 LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] graphics  grDevices utils     datasets  stats     grid      methods   base     

other attached packages:
[1] ggplot2_0.9.0  reshape2_1.2.1 plyr_1.7.1    

loaded via a namespace (and not attached):
 [1] colorspace_1.1-1   dichromat_1.2-4    digest_0.5.2       MASS_7.3-18        memoise_0.1        munsell_0.3       
 [7] proto_0.3-9.2      RColorBrewer_1.0-5 scales_0.2.0       stringr_0.6       
> 

However, as per comments and the answer below, there are better options

> packageVersion("snow")

[1] ‘0.3.9’

Or:

"Rmpi" %in% loadedNamespaces()