Can't search (on SO, with Lucene) for R language's %in% (set membership) operator, even with quotes. (Note that Lucene's default behavior without quotes is even worse than returning no hits, it strips both '%'s and gives tons of irrelevant hits.)

Here is one such answer which cannot be found by searching for '%in%' (It's in Jouni's answer, admittedly inside a <code> tag)

Note that I'm searching for %in% , not the %+% in the title of that question.

PS: as ever, I'm not expecting this ever to happen, just letting R users know:

Bad clunky workaround: search for [R] "set membership" operator

UPDATE: fixed end 2012

  • This is tangentially related to this question (Which by the way, doesn't show up if you search for 'lucene' instead of 'lucene.net')
    – M. Tibbits
    Aug 3, 2011 at 22:38

2 Answers 2


Updated: As with the question about searching for names.functions(), I believe this is a problem with Lucene.Net's parsing of code. If, for example, you search "<code>%in%</code>" +"numpy" it does show up in the results. (I had to add 'numpy' so that it wouldn't return a hundred thousand results.)

Note that the question with this answer actually has <code>%in%</code> not just %in% and perhaps it's Lucene's handling of the <code>.


You can now search for symbols. To do so, just wrap it in quotes for an exact match, like this: "%in%"

  • Awesome. (Make sure to remember the quotes, otherwise you will get no matches)
    – smci
    Jan 15, 2013 at 0:29

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