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Questions tagged [string-matching]

String matching is the problem of finding occurrences of one string (“pattern”, “needle”) in another (“text”, “haystack”).

There are two types of string matching:

  • Exact
  • Approximate

Exact string matching is the problem of finding occurrence(s) of a pattern string within another string or body of text. (NIST). For example, finding CGATCGATTA in CTAGATCCTGCGATCGATTAAGCCTGA.

A comprehensive online reference of string matching algorithms is Exact String Matching Algorithms by Christian Charras and Thierry Lecroq.

Approximate string matching, also called fuzzy string matching, searches for matches based on the edit distance between the pattern and the text.

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javascript regular expression to check for IP addresses

I have several ip addresses like: 115.42.150.37 115.42.150.38 115.42.150.50 What type of regular expression should I write if I want to search for the all the 3 ip addresses? Eg, if I do 115.42.150.* (I will be able to search for all 3 ip…
KennC.
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Regular Expression Arabic characters and numbers only

I want Regular Expression to accept only Arabic characters, Spaces and Numbers. Numbers are not required to be in Arabic. I found the following expression: ^[\u0621-\u064A]+$ which accepts only only Arabic characters while I need Arabic characters,…
moujtahed
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How to do whole-word search similar to "grep -w" in Vim

How do I do a whole-word search like grep -w in Vim, which returns only lines where the sought-for string is a whole word and not part of a larger word? grep -w : Select only those lines containing matches that form whole words. Can this be done in…
user1420463
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Regex allow a string to only contain numbers 0 - 9 and limit length to 45

I am trying to create a regex to have a string only contain 0-9 as the characters and it must be at least 1 char in length and no more than 45. so example would be 00303039 would be a match, and 039330a29 would not. So far this is what I have but I…
NewToRegEx
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How to select R data.table rows based on substring match (a la SQL like)

I have a data.table with a character column, and want to select only those rows that contain a substring in it. Equivalent to SQL WHERE x LIKE '%substring%' E.g. > Months = data.table(Name = month.name, Number = 1:12) > Months["mb" %in% Name] Empty…
Corvus
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Perl - If string contains text?

I want to use curl to view the source of a page and if that source contains a word that matches the string then it will execute a print. How would I do a if $string contains? In VB it would be like. dim string1 as string = "1" If…
Hellos
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How can I match fuzzy match strings from two datasets?

I've been working on a way to join two datasets based on a imperfect string, such as a name of a company. In the past I had to match two very dirty lists, one list had names and financial information, another list had names and address. Neither had…
A L
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Are Regular Expressions a must for programming?

Are Regular Expressions a must for doing programming?
nonopolarity
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Most efficient way to check if $string starts with $needle in perl

Given two string variables $string and $needle in perl, what's the most efficient way to check whether $string starts with $needle. $string =~ /^\Q$needle\E/ is the closest match I could think of that does what is required but is the least…
Stephane Chazelas
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php string matching with wildcard *?

I want to give the possibility to match string with wildcard *. Example $mystring = 'dir/folder1/file'; $pattern = 'dir/*/file'; stringMatchWithWildcard($mystring,$pattern); //> Returns true Example 2: $mystring = 'string bl#abla;y'; $pattern =…
dynamic
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Finding how similar two strings are

I'm looking for an algorithm that takes 2 strings and will give me back a "factor of similarity". Basically, I will have an input that may be misspelled, have letters transposed, etc, and I have to find the closest match(es) in a list of possible…
Daniel Magliola
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Pandas text matching like SQL's LIKE?

Is there a way to do something similar to SQL's LIKE syntax on a pandas text DataFrame column, such that it returns a list of indices, or a list of booleans that can be used for indexing the dataframe? For example, I would like to be able to match…
naught101
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Using Java Regex, how to check if a string contains any of the words in a set ?

I have a set of words say -- apple, orange, pear , banana, kiwi I want to check if a sentence contains any of the above listed words, and If it does , I want to find which word matched. How can I accomplish this in Regex ? I am currently calling…
user193116
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Efficient string matching in Apache Spark

Using an OCR tool I extracted texts from screenshots (about 1-5 sentences each). However, when manually verifying the extracted text, I noticed several errors that occur from time to time. Given the text "Hello there ! I really like Spark ❤️!", I…
mrtnsd
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Algorithm to find out whether the matches for two Glob patterns (or Regular Expressions) intersect

I'm looking at matching glob-style patterns similar the what the Redis KEYS command accepts. Quoting: h?llo matches hello, hallo and hxllo h*llo matches hllo and heeeello h[ae]llo matches hello and hallo, but not hillo But I am not matching…
chakrit
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