What is a permuted index?

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青春惊慌失措
青春惊慌失措 2021-02-18 14:01

I am reading Accelerated C++. I don\'t understand Exercise 5-1:

Design and implement a program to produce a permuted index from the following input. A per

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  • 2021-02-18 14:53

    You can find a 'live' example of a permuted index in the 7th Edition UNIX™ Programmer's Reference Manual, Vol 1 (dating back to 1979). A fragment of it (from the PDF files) is:

    Extract from start of Permuted Index for 7th Edition Unix Programmer's Reference Manual Vol 1

    If you look for 'account', you can find a number of related entries together. You probably wouldn't think to look for sa(1) as well as ac(1), not to mention acct(2) or acct(5) unless they were grouped together. This is the benefit of a permuted index; you can look up the key word and see it in a bigger context.

    You could also look at the man page entry for the ptx(1) command in the same 7th Edition manual.

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  • 2021-02-18 14:54

    Permuted index is an alphabetic list of index surrounded by its context. In the output, observe the bold words. They are alphabetically sorted and are surrounded by its context. This makes it easy for us to search a word and directly infer its usage from the surrounding context i.e. words in your case.

    The quick brown fox

    jumped over the fence

    The quick brown fox

    jumped over the fence

    jumped over the fence

    The quick brown fox

    jumped over the fence

    The quick brown fox

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  • 2021-02-18 15:01

    The term permuted index is another name for a KWIC index, referring to the fact that it indexes all cyclic permutations of the headings. Books composed of many short sections with their own descriptive headings, most notably collections of manual pages, often ended with a permuted index section, allowing the reader to easily find a section by any word from its heading. This practice is no longer common.

    From: http://en.wikipedia.org/wiki/Key_Word_in_Context

    ps: you can access wikipedia via http://www.proxify.com

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