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I'm trying to create a string pattern which will match either (with quotes included):

  • "x by y"
  • x by y
  • 'x by y'

I've tried to use the following pattern: "\"" ~~ ___ ~~ "by" ~~ ___ ~~ "\"" which only matches something with " and tried to find an "or" symbol similar to regex | but to no avail.

Question: What symbols / tools can I use to develop a pattern which matches the above cases?

Question: What is the "correct" translation from a regex approach to a Mathematica approach? Are they the same?

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  • $\begingroup$ For string patterns there is also | (Alternatives) as can be seen here where regex - which can also be used directly - are compared with string patterns. $\endgroup$ – gwr Feb 7 at 7:29
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Here is how I would do it:

quotePattern = { "\"" , "'", "" };
stringPattern = quotePattern ~~ __ ~~ "by" ~~ __ ~~ quotePattern;

StringMatchQ[ #, stringPattern ] & /@ { "x by y", "\"x by y\"", "'x by y'" }

{ True, True, True }

Edit

Be careful what you wish for ... as they say: The OP wants to extract "title by author" from a list of strings I assume. For example:

string = "Some surrounding text. \"The Machine That Changed the World\" by Womack, Jones, and Roos. And it fails.";

Now the above pattern will of course not work. We have to be more precise:

quotePatternMod = { "\"", "'" };
StringCases[ string,
    Shortest[a : quotePatternMod ~~ b : __ ~~ c : "by" ~~ d : ___ ~~ "."] :> a ~~ b ~~ c ~~ d
] 

{"\"The Machine That Changed the World\" by Womack, Jones, and Roos"}

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  • $\begingroup$ I have a follow up question, if you don't mind. I'm trying to use StringCases using the pattern you provided to this string "Some surrounding text. \"The Machine That Changed the World\" by \ Womack, Jones, and Roos. And it fails." And it fails to extract the matching string. Am I using something wrong? $\endgroup$ – Jeel Shah Feb 7 at 7:50
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    $\begingroup$ @JeelShah You will have to add Shortest to the pattern otherwise the whole string will match. $\endgroup$ – gwr Feb 7 at 7:54
  • $\begingroup$ @Jeel What should be the string that is extracted in the case you gave? If it were "booktitle by authors" then you might want to go for a period at the end. $\endgroup$ – gwr Feb 7 at 8:02
  • $\begingroup$ It should be "The Machine That Changed the World" by Womack, Jones, and Roos. and only that. I changed the pattern to: Shortest[quotePattern ~~ __ ~~ quotePattern ~~ "by" ~~ ___ ~~ "."] which removes the "And it fails." however, it keeps the preceding string. Is there a way to force that only something which fits that pattern completely is selected? I tried putting "Some surrounding text." in quotes and that was also extracted. StringCases["\"Some surrounding text.\" \"The Machine That Changed \ the World\" by Womack, Jones, and Roos [0]. And it fails.", \ stringPattern] $\endgroup$ – Jeel Shah Feb 7 at 8:06
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    $\begingroup$ @Jeel name : pattern simply names a pattern you can find it under Pattern in the documentation. $\endgroup$ – gwr Feb 7 at 8:30

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