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Re^5: Data managing problem

by BrowserUk (Pope)
on Feb 22, 2013 at 14:10 UTC ( #1020168=note: print w/replies, xml ) Need Help??

in reply to Re^4: Data managing problem
in thread Data managing problem

The printf is used to ensure that should the line numbers jump from single digit to two

The sprintf pads the lines numbers with leading zeros so the sort correctly. Ie so that they do not sort as:

1 10 11 ... 2 20 21 22 ... 3 30 31 32 33

%05u means we can correctly sort files with upto 99999 lines. If you need more change the number in the format.

Does the sort at the end assume that the input ( and the required output after removing rows ) is sorted

Why would sort "assume its input was sorted"? We are sorting them because we know they will not be. That's why we added the line numbers so that we can put the, back into the input ordering. Perhaps the following where I've left the line numbers in place will clarify things?

C:\test>perl -anle"$h{ $F[1] } = sprintf qq[%05u%s], $., $_; }{ print +for sort values %h" 1/2/2013 cgoo nreuiheru 1/4/2013 doow reiqrqueih 1/5/2013 hellio ruieqrhfuepqh 1/20/2013 cgoo 3rhquh4ureyh 1/30/2013 yetil jerqohgqrij 2/13/2013 hellio rueqipheruh 2/14/2013 cgoo wehrig4r74378 ^Z 000021/4/2013 doow reiqrqueih 000051/30/2013 yetil jerqohgqrij 000062/13/2013 hellio rueqipheruh 000072/14/2013 cgoo wehrig4r74378

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Re^6: Data managing problem
by tmharish (Friar) on Feb 22, 2013 at 14:17 UTC
    Why would sort "assume its input was sorted"?

    I assumed, incorrectly, that you were using the sorted nature of the dates ( and now realize that will not work anyway ... ) to get back the order the hashing messed up - but :

    Perhaps the following where I've left the line numbers in place will clarify things?

    Certainly does - Thank you!

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