From: Brian Candler <b.candler@...>
Date: 2011-05-18T17:14:43+09:00
Subject: Re: Linux utility with reverse index facility?

unknown wrote in post #998974:
> awk &stuff can "give me the the Nth element",
> but, without writing your own search-loop,
> what can "give me the index of the 'element'
> which is <elementValue>" ?
>
> I think it's called 'reverse indexing' ?
>
> == TIA.

>> a = ["foo","bar","baz"]   # note: indexes are 0,1,2
=> ["foo", "bar", "baz"]
>> a.index("bar")
=> 1
>> a.grep(/ba/)
=> ["bar", "baz"]
>> a.each_with_index.select { |line,n| line =~ /ba/ }
=> [["bar", 1], ["baz", 2]]

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