[R] calculations on columns with partially matching names

[Jim Bouldin]

Is there a command for partial matching of character strings? Specifically,
I'd like to be able to calculate the mean of the values in any columns in a
data frame or matrix that have identity in part of their column names.  For
example, columns labeled "mpw06a" and "mpw06b" match on the first five
characters; their mean would be taken whereas any columns beginning with
other than "mpw06" would be excluded.  I need to compare every pair of
columns in the frame, and in some cases, possibly three at a time. 

Thanks in advance for any ideas.




Jim Bouldin
Research Ecologist
Department of Plant Sciences, UC Davis
Davis CA, 95616
530-554-1740