At 02:49 AM 4/22/2006, William Stokes wrote:
I have a column in DB that contains this kind of data,
A20,B16,B17C14,C15,D13,D12 etc.
I would like to print this data to a page and sort it ascending by the
letter an descending by the number. Can this be done? Like
A20
B17
B16
C15
C14
D13
D12
Will, I can think of two ways to do this.
One way involves splitting each value into its two components so you
can sort one ASC & the other DESC.
(First off, I'd seriously consider storing them in two separate DB
fields. If you can do this, your problem is over because you can
extract them in a query in just the order you want. If you're
sorting them in opposite directions that's a pretty good clue that
they're really separate data and should be stored separately.)
But you can split them on the fly in PHP. You can run preg_match()
on each element of your array with a RegExp something like:
/(\D)(\d+)/
(one non-numeric character followed by one or more numeric digits)
preg_match("/(\D)(\d+)/", $aData($i), $aMatches)
is going to produce an array like:
$aMatches = array(
[0] = A20
[1] = A
[2] = 20
)
Build a workspace array using those three match values, sort the way
you want on [1] & [2], and extract your result array from [0].
An alternative way to do this, trickier but probably much faster, is
to translate the initial letter into a value that's its inverse:
$aFrom = array("A","B","C",..."Z");
$aTo = array("Z","Y","X",..."A");
$aTemp = str_replace($aFrom, $aTo, $aData);
This will translate the letters in all the elements of the data array
into their inverse:
B16 --> Y16
A20 --> Z20
B17 --> Y17
...
Then just do a reverse sort on $aTemp and you get:
Z20
Y17
Y16
Then translate the letters back to their original values and you get:
A20
B17
C16
Voila.
Paul
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