Get list of installed packages and their details in R

When we need packages in R we install them. May be some time you wanted to have a look what packages were installed in your system and also what there version numbers are. Although rarely you would like to do this, here is a small tip on how to do it.

Launch R and execute the following command

> packinfo <- installed.packages ()

This will return a list of packages installed and a lot of other details like Version, License, LibPath indicating where it is installed etc. Check out what information is given by executing

> colnames (packinfo)
 [1] "Package"   "LibPath"   "Version"   "Priority"  "Depends"   "Imports"  
 [7] "LinkingTo" "Suggests"  "Enhances"  "OS_type"   "License"   "Built" 

Now simply display the Package and Version fields to have a look at the list of package installed in your system.

> packinfo[,c("Package", "Version")]
.
.
output truncated
.
.

If you know the package name and want to see the version then you can just provide the list of package name strings, for example

> packinfo[c("RANN", "fpc", "RSNNS", "elmNN"),c("Package", "Version")]
      Package Version
RANN  "RANN"  "2.1.3"
fpc   "fpc"   "1.2-4"
RSNNS "RSNNS" "0.4-3"
elmNN "elmNN" "1.0"

This post was a derivative of my answer here in stackoverflow