Creating and pushing to arrays - php

Question

I am trying to create an array(if it does not already exist) and then push values to it.
foreach($playlist->items as $item) {
$str = $item->snippet->title;
$id = $item->snippet->resourceId->videoId;
$substring = substr($str, 0, 5);
$substring = strtolower($substring);
if (is_array($substring)) {
array_push($substring, $id);
}
else {
$substring = array();
array_push($substring, $id);
}
array_push($artists, $substring);
}
I am iterating through data retrieved from a Youtube playlist, so I go through each item with foreach which holds a 'title' - the artist and an 'id' - the video Id . I substring each title and try to use this to group artists into specific arrays.
If an array already exists for that artist, I try to push the 'id' onto the end of that array. If an array does not exist, I create one and then push the 'id' onto that array.
At the end I try to push each artist array into the 'artists' array.
What I get when I print out $artists array is something like this
Array
(
[0] => Array
(
[0] => 1_YUrdjLyAU
)
[1] => Array
(
[0] => Gp8lDW2LUM0
)
...
[543] => Array
(
[0] => Exa0CzlCb3Y
)
Every single $id is in it's own array when they should be grouped together based on $substring. e.g
Array
(
[0] => Array
(
[0] => 1_YUrdjLyAU
[1] => 1_YUrdjLyAU
[2] => 1_YUrdjLyAU
[3] => 1_YUrdjLyAU
[4] => 1_YUrdjLyAU
)
[1] => Array
(
[0] => Gp8lDW2LUM0
[1] => 1_YUrdjLyAU
[2] => 1_YUrdjLyAU
[3] => 1_YUrdjLyAU
)
What am I not understanding?

Answer 1

Here is a simpler solution to your problem:
$artists = array();
foreach($playlist->items as $item) {
$artist = $item->snippet->artist; // however the artist name is fetched..
$id = $item->snippet->resourceId->videoId;
$artists[$artist][] = $id
}
This way, you don't need to check if an artist is already in the array, it will do that automatically and append the video id to the artist.
The $artists array will be assosiative, I don't think you can do it with a numeric array.
The array will look like this:
Array
(
['Jon Lajoie'] => Array
(
[0] => 1_YUrdjLyAU
[1] => lf3hflkap39
[2] => 1vt1455zzbe
[3] => 6dthg3drgjb
[4] => jfop3ifjf3p
)
['Lonely Island'] => Array
(
[0] => Gp8lDW2LUM0
[1] => 5he5hj67j7r
[2] => krt7tkktzk8
[3] => we54w4ggsrg
)
)

Answer 2

Use substring as array key and do following:
**Remove**
if (is_array($substring)) {
array_push($substring, $id);
}
else {
$substring = array();
array_push($substring, $id);
}
array_push($artists, $substring);
**Replace**
$artist[$substring][]=$id;