On Oct 1, 2009, at 12:18 AM, cls59 wrote
PDXRugger wrote:
Considering your instructions:
#Define words to find
to.find <- c( 'the', 'is', 'are' ,'dr')
#Read in the file...
file.text <- readLines( 'data/letter.txt' )
#Count number of occurnces of deined word in text
line.matches <- unlist( lapply( to.find, grep, x =
unlist(file.text[2]) )
)
Result:
line.matches
[1] 1 1 1
This is not right of course as there are actually four words and
secondly
becasue the searched words appear multiple times.
The example I gave was only meant to identify those lines on which
matches
occurred. Using x = unlist(file.text[2]) only feeds one line of the
file
into the matching routine so the result indicates that all the
matches were
on line 1-- the only line present for searching.
If you want to count the individual occurrences of the words on each
line,
you may need to look at using a function such as gregexpr. grep only
indicates if a match or matches is present in a line of text--
gregexpr
indicates at which positions those matches occur in the line.
However, you may be getting to the point with this where R is no
longer an
appropriate tool for this job. R is amazingly flexible it is
possible that
it can give you what you want. However, R was not designed to
perform text
processing-- Perl comes to mind as being a language that was
explicitly
designed to perform these sorts of operations.
Perhaps you should use the R-search facilities for such questions:
http://finzi.psych.upenn.edu/R/library/tau/html/00Index.html
http://finzi.psych.upenn.edu/views/NaturalLanguageProcessing.html
http://www.jstatsoft.org/v25/i05/
R may not have been designed for text processing, but it is rather
amazing how much has been done.
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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