28 lines
866 B
R
28 lines
866 B
R
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library(foreach)
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# define a combine function that writes the results to a file.
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# note that the first argument is not a result, but the file
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# object, and must be specified via the .init argument and
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# returned as the value of this function.
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output <- function(fobj, ...) {
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lines <- list(...)
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cat(sprintf('writing %d line(s)\n', length(lines)))
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writeLines(unlist(lines), con=fobj)
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fobj
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}
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# create a temporary file to write the results to
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fname <- tempfile('foreach')
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fobj <- file(fname, 'w')
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# use ireadLines to create an iterator over the lines of the input file,
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# which are converted to upper case, and processed by the output function
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foreach(input=ireadLines('output.R'), .combine=output, .init=fobj,
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.multicombine=TRUE, .maxcombine=5) %do%
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toupper(input)
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# display the results and clean up
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close(fobj)
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file.show(fname)
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file.remove(fname)
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