[RESOLVED] calculating a streak / run

sgray

Hi all,

I have some data in a field which is either A or B. I'd like to calculate the 'biggest streak' by measuring how many times A appears in a row, and how many B does. The format is basically this:

id date winner

1 01/02/12 A
2 01/02/12 B
3 03/02/12 A
4 05/03/12 A

So in this example A would have a largest streak of 2, and B just 1. The data is coming from a MYSQL query and I'm just running through the results in a while loop.

There's probably a simple way but it's late and my brains mush. Any help appreciated 🙂

Cheers

NogDog

I'm thinking that you could simply(?) append your query results for that field into a string, then do a little regex-ing and array manipulation:

<?php
$test = 'ABAAABBABBBBAABBAAAAAAABBABBAB';

$longestA = '';
$longestB = '';
preg_match_all('/(A+)|(B+)/', $test, $matches);
$As = array_filter($matches[1]);
if(count($As)) {
	sort($As);
	$longestA = array_pop($As);
}
$Bs = array_filter($matches[2]);
if(count($Bs)) {
	sort($Bs);
	$longestB = array_pop($Bs);
}
echo "Test data: '$test'";
echo "<br />\n";
echo "Longest streak of 'A': ".strlen($longestA)." ($longestA)";
echo "<br />\n";
echo "Longest streak of 'B': ".strlen($longestB)." ($longestB)";

(I'm sure you could clean that up a bit to reduce the code duplication, but it should give you the idea. 🙂 )

sgray

thank you kind sir, didn't think of doing it like this. Works a treat 🙂

NogDog

I suppose the downside of that approach might be if the data sample ever gets to be so large that the resulting string becomes inconveniently long. 🙂