Regexec(): This function searches a character vector for a regular expression, much like regexpr(), but it will additionally return the locations of any parenthesized sub-expressions. Sub(), gsub(): Search a character vector for regular expression matches and replace that match with another string Regexpr(), gregexpr(): Search a character vector for regular expression matches and return the indices of the string where the match begins and the length of the match grepl() returns a TRUE/ FALSE vector indicating which elements of the character vector contain a match grep() returns the indices into the character vector that contain a match or the specific strings that happen to have the match. Grep(), grepl(): These functions search for matches of a regular expression/pattern in a character vector. The primary R functions for dealing with regular expressions are
22.4 Example: Bootstrapping a Statistic. 21.3.2 Changes in PM levels at an individual monitor. 21.2 Loading and Processing the Raw Data. 21 Data Analysis Case Study: Changes in Fine Particle Air Pollution in the U.S. 15.3 Lexical Scoping: Why Does It Matter?. 15.1 A Diversion on Binding Values to Symbol. 12.3.1 Common dplyr Function Properties. 12 Managing Data Frames with the dplyr package. 9.5 Extracting Multiple Elements of a List. 9.4 Subsetting Nested Elements of a List. 7 Using Textual and Binary Formats for Storing Data. 5.4 Calculating Memory Requirements for R Objects. 5.3 Reading in Larger Datasets with read.table. 5.2 Reading Data Files with read.table(). 3.2 Getting started with the R interface. Linux: Traverse Directory: find, xargs Count Char, Word, Lines wcĬount the number of chars, words, lines. Linux: Sort Lines Processing Multiple Files Show only first few lines of a huge file head filename Grep 'html HTTP' apache.log | awk '' filename More Grep Examples # print lines containing “html HTTP” in a log file, show only the 12th and 7th columns, show only certain lines, then sort, then condense repeation with count, then sort that by the count. Print just file name that does NOT match. Print just file name do NOT print the matched lines. grep -r -include='*html' pattern dirName = search files for pattern in dirName including subdirs, but only files ending in “.html”. *.html = search all files ending in “.html”, in current dir. Grep -P 'png HTTP|jpg HTTP' *log Options for File Selection Grep -v 'html HTTP' *log # print lines containing “png HTTP” or “jpg HTTP” (Perl and Python's regex are basically compatible.)Įxamples: # print lines not matching a string, for all files ending in “log” Most Useful Grep Options Options for Pattern String -F Grep -r -file=myPattern.txt -include=*js. The regex is stored in file named myPattern.txt R grep unique code#
Example: # search js source code in dir and all subdirs.
This is useful when you want to search complicated string in source code, such as your string is really complicated, you can put it in a file, and use the option -file= my_pattern_filename for the search text.
(F means “Fixed string”) # search ruby source files that contains. Match file name by a glob pattern ( * is a wildcard that matches 0 or more any char.). Grep 'xyz' *html Grep for All Files in a Dir # show matching lines in dir and subdir, file name ending in html Grep 'xyz' myFile # show lines containing xyz in all files ending in html in current dir top level files Show Matching Lines # show lines containing xyz in myFile They are especially useful for processing lines. This page is a basic tutorial on using Linux shell's text processing tools.
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