[R] using a regular expression
r at catwhisker.org
Sun Sep 11 15:50:14 CEST 2016
On Sat, Sep 10, 2016 at 07:23:37PM +0000, Glenn Schultz wrote:
> Below is the function that I am writing. I am using sed to replace the hex characters. First, to get past NUL I use sed to replace hex 00 with hex 20. This has worked. Once the Nul is removed and can successfully parse the file with ReadLine sub_str. This final step before delimiting the file and making it nice and tidy is to remove the hex 20 characters. I am using the same strategy to eliminate the spaces and sed command works in a shell but does not work in the R function. What am I doing wrong? I have dput - some of the nastier lines with hex 20 characters below my code.
I believe that you will find that the sed "d" command deletes the
"pattern space" (in a simple text file, it would delete the line) in
which the specified regular expression is found.
I suspect that you actually want to eliminate the "space" characters
themselves, so rather than:
> # The file has been parsed accroding to length 400 for each data element.
> # The next step is to remove all the trailing white space hex character
> # x20
> sedcommand2 <- paste("sed -e '/\\x20/d' <",
what is wanted is:
sedcommand2 <- paste("sed -e 's/\\x20//g' <",
Note that you might consider using R's gsub() function to perform that
"space elimination"both natively and a bit earlier.
David H. Wolfskill r at catwhisker.org
Those who would murder in the name of God or prophet are blasphemous cowards.
See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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