how to check if a library is loaded, from a function

Mon, Jan 31, 2011 8:04 PM

Hi,

I've written a function which I load with a source command. 
  The function requires a certain library, phangorn, to work.

I would like the function to check if phangorn is loaded as 
a library before running.  For some reason, just putting 
require(phangorn) into the sourced function doesn't do anything.

This must be simple, but I can't figure it out!  Any help 
appreciated...

Cheers!
Nick

====================================================
Nicholas J. Matzke
Ph.D. Candidate, Graduate Student Researcher

Huelsenbeck Lab
Center for Theoretical Evolutionary Genomics
4151 VLSB (Valley Life Sciences Building)
Department of Integrative Biology
University of California, Berkeley

Graduate Student Instructor, IB200B
Principles of Phylogenetics: Ecology and Evolution
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"[W]hen people thought the earth was flat, they were wrong. 
When people thought the earth was spherical, they were 
wrong. But if you think that thinking the earth is spherical 
is just as wrong as thinking the earth is flat, then your 
view is wronger than both of them put together."

Isaac Asimov (1989). "The Relativity of Wrong." The 
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how to check if a library is loaded, from a function

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