note 67936 deleted from function.usort by danbrown
| From: | danbrown@php.net | Date: | Sun, 23 Jan 2011 16:26:42 +0000 |
| Subject: | note 67936 deleted from function.usort by danbrown | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-176067@lists.php.net to get a copy of this message | ||
Note Submitter: g8z at yahoo dot com
----
<?php
/**
This sort function allows you to sort an associative array while "sticking" some fields.
$sticky_fields = an array of fields that should not be re-sorted. This is a method of achieving
sub-sorts within contiguous groups of records that have common data in some fields.
For example:
$a = array();
$a []= array(
'name' => 'Sam',
'age' => 23,
'hire_date' => '2004-01-01'
);
$a []= array(
'name' => 'Sam',
'age' => 44,
'hire_date' => '2003-03-23'
);
$a []= array(
'name' => 'Jenny',
'age' => 20,
'hire_date' => '2000-12-31'
);
$a []= array(
'name' => 'Samantha',
'age' => 50,
'hire_date' => '2000-12-14'
);
$sticky_fields = array( 'name' );
print_r( stickysort( $a, 'age', DESC_NUM, $sticky_fields ) );
OUTPUT:
Array
(
[0] => Array
(
[name] => Sam
[age] => 44
[hire_date] => 2003-03-23
)
[1] => Array
(
[name] => Sam
[age] => 23
[hire_date] => 2004-01-01
)
[2] => Array
(
[name] => Jenny
[age] => 20
[hire_date] => 2000-12-31
)
[3] => Array
(
[name] => Samantha
[age] => 50
[hire_date] => 2000-12-14
)
)
Here's why this is the correct output - the "name" field is sticky, so it cannot
change its sort order. Thus, the "age" field is only sorted as a sub-sort within records
where "name" is identical. Thus, the "Sam" records are reversed, because 44 >
23, but Samantha remains at the bottom, even though her age is 50. This is a way of achieving
"sub-sorts" and "sub-sub-sorts" (and so on) within records of identical data for
specific fields.
Courtesy of the $5 Script Archive: http://www.tufat.com
**/
define( 'ASC_AZ', 1000 );
define( 'DESC_AZ', 1001 );
define( 'ASC_NUM', 1002 );
define( 'DESC_NUM', 1003 );
function stickysort( $arr, $field, $sort_type, $sticky_fields = array() ) {
$i = 0;
foreach ($arr as $value) {
$is_contiguous = true;
if(!empty($grouped_arr)) {
$last_value = end($grouped_arr[$i]);
if(!($sticky_fields == array())) {
foreach ($sticky_fields as $sticky_field) {
if ($value[$sticky_field] <> $last_value[$sticky_field]) {
$is_contiguous = false;
break;
}
}
}
}
if ($is_contiguous)
$grouped_arr[$i][] = $value;
else
$grouped_arr[++$i][] = $value;
}
$code = '';
switch($sort_type) {
case ASC_AZ:
$code .= 'return strcasecmp($a["'.$field.'"],
$b["'.$field.'"]);';
break;
case DESC_AZ:
$code .= 'return (-1*strcasecmp($a["'.$field.'"],
$b["'.$field.'"]));';
break;
case ASC_NUM:
$code .= 'return ($a["'.$field.'"] -
$b["'.$field.'"]);';
break;
case DESC_NUM:
$code .= 'return ($b["'.$field.'"] -
$a["'.$field.'"]);';
break;
}
$compare = create_function('$a, $b', $code);
foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
usort ( $grouped_arr[$grouped_arr_key], $compare );
$arr = array();
foreach($grouped_arr as $grouped_arr_key=>$grouped_arr_value)
foreach($grouped_arr[$grouped_arr_key] as $grouped_arr_arr_key=>$grouped_arr_arr_value)
$arr[] = $grouped_arr[$grouped_arr_key][$grouped_arr_arr_key];
return $arr;
}
?>