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File: UnexpectedInteractionOfFeatures

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********
!!! An Unexpected Interaction of Features

I've been dealing with some data, and using my usual technique
of using command-line tools to play with it for a while before
writing a program to do the full analysis.

But something was wrong, and it took me a while to work it out.

I was sorting a file:

|>>
| which _ aerodynamically _ electroencephalogram _ exotically _ aerodynamically _ a _ differentiation | *->* | a _ aerodynamically _ aerodynamically _ differentiation _ electroencephalogram _ exotically _ which |
<<|

But my file has as the first field a count:

|>>
| 5 which _ 15 aerodynamically _ 20 electroencephalogram _ 10 exotically _ 15 aerodynamically _ 1 a _ 15 differentiation | *->* | 10 exotically _ 15 aerodynamically _ 15 aerodynamically _ 15 differentiation _ 1 a _ 20 electroencephalogram _ 5 which |
<<|

That's not what I wanted, but this was a game I'd played before. The
utility *sort* is working on the data as text, so it's alphabetical.
I need to sort using *-n* to get it to sort numerically:

|>>
| 5 which _ 15 aerodynamically _ 20 electroencephalogram _ 10 exotically _ 15 aerodynamically _ 1 a _ 15 differentiation | *->* | 1 a _ 5 which _ 10 exotically _ 15 aerodynamically _ 15 aerodynamically _ 15 differentiation _ 20 electroencephalogram |
<<|

Excellent, but now I realise there are repeated lines, and I need
to de-duplicate.  So I use *sort*-u* to do that:

|>>
| 5 which _ 15 aerodynamically _ 20 electroencephalogram _ 10 exotically _ 15 aerodynamically _ 1 a _ 15 differentiation | *->* | 10 exotically _ 15 aerodynamically _ 15 differentiation _ 1 a _ 20 electroencephalogram _ 5 which |
<<|

The duplication is gone, but the screwy ordering is back, because
I forgot the "numerical" flag, so *sort*-nu* is what I need:

Spot the difference.

Yes, the "differentiation" line has gone, and I can only assume that
when both the *n* and *u* flags are set, it only takes the numbers
into account when deciding if there are duplicates.  I haven't explored
whether, for a given number, it (a) sorts and keeps the first, (b) sorts
and keeps the last, (c) keeps the first in the input then sorts, (d)
keeps the *last* in the input then sorts, or (e) something else.

But it's certainly not what I expected.

So now it's back to using "sort -n | uniq" rather than "sort -nu".

For reference: "sort --version" returns "sort (GNU coreutils) 8.21"

----

|>>
| |>> <<<< Prev <<<< ---- ArchimedesHatBoxTheorem <<| | : | |>> >>>> Next >>>> ---- WhyTopPostingHasWon ... <<| |
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