[R] How can I check a package is installed or not?

[Duncan Murdoch]

On 11-09-27 3:19 PM, Fabrice Tourre wrote:
> Dear list,
>
> How can I detect a package is installed or not? If not, then install it.

Here's one way.  This might be slow if you have all of CRAN installed, 
but it's quick enough if you only have a few dozen packages:

installed <- rownames(installed.packages())

"DESeq" %in% installed

Another way is to use

if (!require("DESeq")) ...

but that will give warnings if DESeq is not there.

Duncan Murdoch

>
> For example, in a script, I want to check the package DESeq is
> installed or not. If not, then I will using this script to install it.
>
> source("http://www.bioconductor.org/biocLite.R")
> biocLite("DESeq")
>
> The pseudo script would be like this:
>
> try:
>      library("DESeq")
> catch:
>      source("http://www.bioconductor.org/biocLite.R")
>      biocLite("DESeq")
>
> Thank you
>
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