8/10/2023 0 Comments Grep lines before and afterFor commentary on Raku's lines routine, see the URL below. Sample Output (examples 3 and 4 that additionally handles pattern in first line as well as consecutive occurrences of pattern): line 1įYI: Raku's lines routine is advertised to act lazily, so potentially a file can be analyzed without having to read-in the entire file first. Sample Output (first 2 examples that delete a 2-line Regex): pattern You can use sed to match a pattern with /pattern/ and let that trigger the commands N and d, which appends the next line to the buffer and then discards both: sed '/pattern/ ' The first two solutions will have issues if the pattern matches on consecutive lines. "Men by nature long to get on to the ultimate truths, and will oftenīe impatient with elementary studies or fight shy of them.I tend only to use grep when extracting single lines from files, so when I need to perform more complicated edits in a text, I use other tools.Īll solutions here assume that the pattern may occur multiple times in the text and will remove the lines on which it occurs and the lines immediately previous to them. > PLEASE do read the posting guide > and provide commented, minimal, self-contained, reproducible code. > Assistant Professor, Wilfrid Laurier University grep -A4 'pattern' infile>outfile, but I don't know if there is an equivalent argument in R. There is an an argument to grep in unix that can do this. The best I can come up with would be to have the program grep the four lines following matching the pattern "Document ". There is no field ID attached to those lines. > I have a series of grep scripts that can extract the date and convert it to a date object, but I can't figure out how to grep the newspaper name. > I have a series of newspaper articles in a text file, downloaded from a text file. > grep("pattern", x = readLines("clipboard")) > # read data in, and only select the 4th line to pass to grep() > cat("Document 1 of 100 \n \n \n Newspaper Name \n \n Day Date", file = > Maybe I don't understand properly.if you are doing this in R, can't I'll just have to come up with a loop to tell R to get the 4th, 8th, 12, 16th, line, etc. But your idea of indexing the text object read into R with the line number where the newspaper name is found is a good one. > I'm using readlines to get the text file into R and then trying to use grep to get the newspaper name for each record. > The file that I have includes up to 100 documents (Document 1, Document 2, Document 3.Document 100) with the newspaper name following 4 lines below each Document number. > Sorry for the insufficient introduction. > should give you 4 lines after each line where Document occurred. > grep("Document .", yourfile, value = FALSE) 4 > If you know you can find the start of the document (say that line I could do two separate commands, but I'd like to know if this could be done in one command. Is there any way to have it grab two different lines after the grep, say the second and the fourth line? There's some other information in the text file I'd like to grab. > If you want a sufficient number of lines that manually writing index becomes cumbersome, you could use something like: > index index > You just need to make sure you avoid recycling, e.g., > Try this (untested as I'm on my iPhone now): and Josh's solution can be shortened to (as he knows): Please read theĭocs, especially the tutorial, An Intro to R. Messages sorted by: īasic basic stuff (not grep - the stuff thereafter).Next message: grep lines before or after pattern matched?.Previous message: grep lines before or after pattern matched?.grep lines before or after pattern matched? Bert Gunter gunter.berton at Grep lines before or after pattern matched?
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