man awk? I've used awk for similar tasks (if I am reading the post correctly.) Google-Fu should turn up some useful examples. Also awk should be on your linux installation in some form or another. Regards, Ken Hutchison
On Oct 4, 2554 BE, at 10:52 PM, "Tom D. Harray" <tomdhar...@gmail.com> wrote: > Hi there, > > I would like to use my linux system's fgrep to search for a text pattern > in a file. Calling system with > > system("fgrep \"SearchPattern\" /path/to/the/textFile.txt") > > works in general, but I need to search for the search pattern at the > beginning of the line. > > The corresponding shell command > > fgrep "^SearchPattern" /path/to/the/textFile.txt > | > |___ here's my problem > > does exactly what I want. I tried various combinations on ", \", \^, but > failed to make system() work. > > How can I call the working shell command including the caret > meta-character with system()? > > Thanks and regards, > > dirk > > > P.S.: Actually I have to search for about 5.000 patterns, stored in an R > list, in a text file with about 30.000.000 lines. The patterns appear in > one or more lines of the text file. Only those lines have to be > extracted if the patterns at the beginning of the line. > > Example with matching line 1, non matching line 2, non-matching line 3 > (line three comprises aaa, but not at the beginning of the line 3): > > SearchPattern = "^aaa" > > Text file: aaaooooooooooo > bbbiiiiiiiiiii > aacttttttttaaa > > Going line by line through the file in R is too slow, and I cannot > program it in C or C++. Hence I use the fgrep command. I would > appreciate if anyone has a fast alternative which works with R on Linux > and Windows systems. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.