[R] convert "1", "10", and "100" to "0001", "0010", "0100" etc.

[Nick Matzke]

Hi,

Is there an easy way to convert numbers into a form such 
that they all have the same number of digits?

e.g.:
"1", "10", and "100"

...become...

"0001", "0010", "0100" etc.

I ask because I am producing a large number of files that 
need to sort consistently by filename.  Currently I get this 
kind of sorting:

filename1
filename10
filename11
filename12
filename13
filename14
filename15
filename16
filename17
filename18
filename19
filename2
filename20
filename21
...etc..

which is annoying.  Ideally I'd have:

filename0001
filename0002
filename0003
filename0004
filename0005
filename0006
filename0007
filename0008
filename0009
filename0010
filename0011
...etc..

Basically I want to produce strings like "0010" without an 
elaborate hack.

Thanks!
Nick




-- 
====================================================
Nicholas J. Matzke
Ph.D. Candidate, Graduate Student Researcher
Huelsenbeck Lab
Center for Theoretical Evolutionary Genomics
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Department of Integrative Biology
University of California, Berkeley

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