sort multi-array is confusing. Help please?

[mojo]

hey all🙂

I've got a nice array going, but need help sorting it. Let's take this array:

$peeps
place IDnum Name duplicate
1 ID890 Mary N
2 ID39 Tom N
3 ID452 James N
4 ID39 Tom N

I want to sort the array by IDnum to find that Tom is a duplicate. Then I'll use a while loop later to set the $peeps['place']['duplicate'] element in that row to = Y. I'm setting the array something like this:
$peeps[1] = array(
"IDnum" => "ID890",
"Name" => "Mary,
"dup" => "N"
);
$peeps[2] = array(
"IDnum" => "ID39",
"Name" => "Tom,
"dup" => "N"
);
$peeps[3] = array(
"IDnum" => "ID452",
"Name" => "James,
"dup" => "N"
);
$peeps[4] = array(
"IDnum" => "ID39",
"Name" => "Tom,
"dup" => "N"
);

Now I want to sort the array and its very important for the rows to stay together. The result should be this:

2 ID39 Tom N
4 ID39 Tom N
3 ID452 James N
1 ID890 Mary N

Can someone help out? I've done some thread searching here already, but still having trouble.

🙂

[jkohns]

don't know if this is what you're looking for, but this function will sort the array as asked- however, it assigns new keys to the resulting array...I included the original key for each element in a new element in the sub-array called 'place'...hope it helps

// use: multisort($array, $element)
// where $array is the array to sort, and $element is the name of the sub-element to sort on
// (only works on a 2-dimensional array)

function multiSort($array, $element){

foreach ($array as $key=>$vals){
	$new_array[$vals[$subelement].$key] = $vals;
	$new_array[$vals[$subelement].$key]['place'] = $key;
}
asort($new_array);
return $new_array;

}

$peeps = multisort($peeps, 'IDnum');

would produce:

Array
(
[ID392] => Array
(
[IDnum] => ID39
[Name] => Tom
[dup] => N
[place] => 2
)

[ID394] => Array
    (
        [IDnum] => ID39
        [Name] => Tom
        [dup] => N
        [place] => 4
    )

[ID4523] => Array
    (
        [IDnum] => ID452
        [Name] => James
        [dup] => N
        [place] => 3
    )

[ID8901] => Array
    (
        [IDnum] => ID890
        [Name] => Mary
        [dup] => N
        [place] => 1
    )

)

[mojo]

hmmm....
is there a way to retain the key? The key is actually the person's place in a list that has to be retained. I'm looking for duplicate entries in the list.
Can I start off the assignments like this:

$peeps[1] = array(
"IDnum" => "ID890",
"Name" => "Mary,
"place" => 1
"dup" => "N"
);

At least before sorting, the "place" is equal to the key. Once the keys are messed up by the sort, how do I reference the Name of the person in place=1?

this wouldn't work $peeps["place"]["name"], would it? Don't I still need to address the array row by its key?

thanks for your help!

😃

[mojo]

Hey JK - scratch that. I'll duplicate the list position in the "place" subelement up front...
$peeps[1] = array(
"IDnum" => "ID890",
"Name" => "Mary,
"place" => 1
"dup" => "N"
);
$peeps[2] ...has ["place"] => 2
$peeps[3] ...and so on and so on...

Then I'll do your multisort on the IDnum... do my dup testing...
when I'm done, I'll just re-multisort on the "place" to put the keys back in order. Does that make sense?

Do I remove the

$new_array[$vals[$subelement].$key]['place'] = $key; line? Or are there more changes? The function wouldn't have to make the "place" element.

thanks again

😃

[jkohns]

Yeah, that line can go...if you include the 'place' subelement in the first place

[mojo]

Cool J/K! 🆒 works!

...but I guess I misunderstood. Taking the above example (just the pointer and the IDnum), before your function there's this:
[1][IDnum] = ID890
[2][IDnum] = ID39
[3][IDnum] = ID452
[4][IDnum] = ID39
After the sort, I get this:
[2][IDnum] = ID39
[4][IDnum] = ID39
[3][IDnum] = ID452
[1][IDnum] = ID890

Now you (or somewhere else I read) said the pointers/indices would be reassigned to the new rows, that's why we saved the 'place' element. I thought I was going to get this (LOL :p )
[1][IDnum] = ID39
[2][IDnum] = ID39
[3][IDnum] = ID452
[4][IDnum] = ID890
...the pointers have been re-assigned here.

OK so I did a print_r($peeps); and yep, the sort worked so thanks!. I have a different prob now traversing the array to find dups. That's clearly a different topic now so I'll start a new thread.

mojo 😉

[minorgod]

I think this might be easier...it should keep your associative array keys intact....This will sort an array of 1-dimensional arrays as such:

$input_array=array(0 => 
                                         array('name' => 'Zeus',
                                                   'email' => '[e-mail]'),

                             1=> 
                                     array('name' => 'Mary',
                                               'email' => '[e-mail]'),
                              2=> 
                                     array('name' => 'Peter',
                                               'email' => '[e-mail]')
                    );


//now to sort on the key 'name' in the input arrays, we would do this:

foreach ($input_array as $val) {
    		 	 $sortarray[] = $val[name];
		}
		array_multisort($sortarray,SORT_ASC,SORT_REGULAR,$input_array);
		unset($sortarray);

//now $input_array will look like this...

                    array(0 => 
                                     array('name' => 'Mary',
                                               'email' => '[e-mail]'),

                              1=> 
                                     array('name' => 'Peter',
                                               'email' => '[e-mail]')

                              2=> 
                                     array('name' => 'Zeus',
                                               'email' => '[e-mail]'),
                    );

//if you wanted to do a numeric sort you would change SORT_REGULAR to SORT_NUMERIC.

That's it. Hope that helps.

Incedentally, to remove your duplicates, just loop through the array and find the $key of the first duplicate, then use array_splice($key) to remove the array element. If the array is sorted, you should only need to check if the current element is the same as the last one and if so remove it. You'd only need to traverse the array once this way.