Multi-dimension array sort help

RobClark

Howdy all..

Need some help sorting a multi-demenions array by date... the array looks something like

$arr[0]["name"] = "Rob";
$arr[0]["age"] = 65;
$arr[0]["date"] = "2002-10-12";
$arr[1]["name"] = "Jim";
$arr[1]["age"] = 23;
$arr[1]["date"] = "2002-12-25";
$arr[2]["name"] = "Mary";
$arr[2]["age"] = 54;
$arr[2]["date"] = "2001-10-12";

What I need to do is order it by date DESC and also reset the keys to the order of the dates... so after sorting the above exmaple would turn to:

$arr[0]["name"] = "Jim";
$arr[0]["age"] = 23;
$arr[0]["date"] = "2002-12-25";
$arr[1]["name"] = "Rob";
$arr[1]["age"] = 65;
$arr[1]["date"] = "2002-10-12";
$arr[2]["name"] = "Mary";
$arr[2]["age"] = 54;
$arr[2]["date"] = "2001-10-12";

Thanks in advance..

cschotch

Check the other forum place "General Discussion" theres a answer that might help there that I just posted....

RobClark

I deleted the other thread... in response to your response..

The array is built from 3 DB queries on seperate tables, with different conditions and so fourth that cant be combined into a single query.....

tomhath

http://www.zend.com/manual/function.array-multisort.php

RobClark

Originally posted by tomhath
http://www.zend.com/manual/function.array-multisort.php

Thanks.. I had read the manual page for that function already at php.net.. the only examples were for sorting on the second set of keys... which is not what I want.. also I believe the key association is maintained...

Do you have a coding exmaple of using array_multisort() to sort on the value when you dont know the first key?

eg: $array[n]["date"] where n can be any integer from 0 upwards in order..

Thanks

tomhath

Didn't read your original post carefully enough. What you need is to define your own comparison function to sort the array:

<?php
$arr[0]["name"] = "Rob"; 
$arr[0]["age"] = 65; 
$arr[0]["date"] = "2002-10-12"; 
$arr[1]["name"] = "Jim"; 
$arr[1]["age"] = 23; 
$arr[1]["date"] = "2002-12-25"; 
$arr[2]["name"] = "Mary"; 
$arr[2]["age"] = 54; 
$arr[2]["date"] = "2001-10-12"; 

function cmp ($a, $b) {
    if ($a["age"] == $b["age"]) return 0;
    return ($a["age"] < $b["age"]) ? -1 : 1;
}

usort ($arr, "cmp");

for ($i=0; $i<count($arr); $i++) {
  echo "<br>" . $i . " ";
  while (list ($key, $value) = each ($arr[$i]) ) {
    echo "  $key: $value";
  }
} 

?>

tomhath

Obviously that sorts by age ascending, but you get the idea. The trick to keep in mind is that php doesn't really have multi-dimensional arrays; it has arrays of arrays.

So all you need to do is write a little function that compares one element in $arr to another element of $arr. Php doesn't care that array element $arr[0] is itself an array.