On Jan 3, 2010, at 6:09 PM, Jim Bouldin wrote:
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.
?grep
?"["
> tdf <- data.frame(mpw06a=rnorm(10), mpw06b=rnorm(10), abc=rnorm(10))
> lapply(tdf[ , grep("mpw06", names(tdf)) ], mean)
$mpw06a
[1] -0.1825447
$mpw06b
[1] -0.2386772
I need to compare every pair of
columns in the frame, and in some cases, possibly three at a time.
?combn
Thanks in advance for any ideas.
Jim Bouldin
Research Ecologist
Department of Plant Sciences, UC Davis
Davis CA, 95616
530-554-1740
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
