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

[Fabrice Tourre]

Thank you for your sharing

I got it.

On Tue, Sep 27, 2011 at 9:44 PM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Sep 27, 2011, at 3:19 PM, Fabrice Tourre wrote:
>
>> Dear list,
>>
>> How can I detect a package is installed or not? If not, then install it.
>>
>> 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(
>
> Perhaps:
>
> if ( require("DESeq") ) {  do-stuff } else {
>               source("http://www.bioconductor.org/biocLite.R")
>               biocLite("DESeq") }
>
> 'require' reports success or failure with a logical and loads the package if
> successful. You need to add logical.return=TRUE to a 'library' call to get
> avoid getting a character value back.
>
>> catch:
>>   source("http://www.bioconductor.org/biocLite.R")
>>   biocLite("DESeq")
>>
>> Thank you
>>
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>
> David Winsemius, MD
> West Hartford, CT
>
>