![]() ![]() That will only matter if you are running this in a really tight loop, but then you should probably optimize further to pass in a list of search strings, and search for them all in a single pass, anyway. This is mildly more complex, but saves one external process compared to the first attempt above. Anyway, I went for a solution which should be portable to regular traditional / POSIX Awk.) (With GNU Awk, you could set the built-in field separator to the regex. Split the line on the search regex and count the number of resulting fields, minus one (if there is no separator, there will be a single field, if it occurs once, the line will be split in two fields, etc). The parentheses allow either end of line ( $ now with its metacharacter meaning) or a character which is not a lowercase or uppercase character after name. The first backslash changes $ from a regex metacharacter which matches end of line, to an expression which simply matches a literal dollar sign. As noted in the comment -w is a GNU extension. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. The expected behavior is that grep only finds the exact match of 'er' in the string below with no partial matches. Select only those lines containing matches that form whole words. The command below finds 'er' in 'großer', and 'weißer'. ![]() (By POSIX, you could equivalently backslash | and the parentheses to enable their use as alternation and grouping characters with plain grep but I find this convention to be weird and the resulting regex will be harder to read). I would like to grep for the exact match of 'er', but grep -w finds a partial match in words with non-Latin letters such as 'ß' in addition to the exact match. The -E option selects extended regular expression syntax which enables some features which were not supported in the traditional original grep. The following assumes counting the number of matching lines is sufficient, and focuses on demonstrating how to write a regex which matches $name only if it is not immediately followed by an alphabetic character or a dollar sign. Prints every match on a separate line ( -o) and only searches for literal matches ( -F) in isolated words ( -w) the pattern is within single quotes, so that it is passed on verbatim to grep and we count the number of generated output lines with a pipe to wc -l.Īlternatively, you could specify a regex with an exact boundary condition. Grep -c (typically) reports the number of matching lines if a line which contains the pattern twice or more should count as multiple matches, you need a different approach. It's not clear what you mean by "word" the requirement that $nameeee should not count as a match suggests the use of the -w option bot its exact semantics of what is a "word" may differ from yours. The $ character is a regex metacharacter which needs to be escaped from the regex engine, too, or you can use the -F flag to turn off regex matching and only select literal matches. If name is not a defined variable, you are actually running grep "" demo.txt after the shell replaces $name with the variable's (nonexistent) value. Since I'm concatenating I'm not really sure of how to use the \b to enforce a full match.Double quotes don't protect the string from string interpolation by the shell. I have also tried concatenating the name part with other numbers like this, but with no success: Relationships <- subset(Relationships, grepl(paste(paste(Names$name, '3', sep = ""), collapse = "|"), Relationships$Results)) This doesn't work, if I use fixed = TRUE than it doesn't return any result at all (which is weird). Relationships <- subset(Relationships, grepl(paste(Names$name, collapse = "|"), Relationships$Results)) Records <- c("ThisIsTheResultIWant", "notThis", "notThis", "notThis") This variable is build like this "WordNumber" but for the same word I have multiple numbers (more than 30), so when I use the grepl expression to get for instance Word1 I get also results that I would like to avoid, like Word12.Īny ideas on how to fix this? Names <- c("Word1") 1 In that case, I'd use grep -q 'user1example\.com\>' - with a line anchor at the start, and an end-of-word anchor at the end.This is based on the comparison between two columns Result and Names. I'm trying to extract certain records from a dataframe with grepl. ![]()
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