merge and create array from two different sized arrays - php

Question

I need to take two arrays, and combine them to look like this. Not sure how. Here are the two arrays.
$items = array( 'activity', 'photos');
$activity_subitems = array ('var1', 'var2', 'var3');
$photo_subitems = array ('var1', 'var2');
I would like it to be in an array like this;
$query_vars = array(
'activity' => 'var1',
'activity' => 'var2',
'activity' => 'var3',
'photos' => 'var1',
'photos' => 'var2'
);

Answer 1

If the resulting array is a dictionary, you can't, because you are creating more than one same Key for multiple Values. If it is not a dictionary, rephrase the question please.
If what you want is to create something like this:
Array (
[activity] => Array (
[0] => var1
[1] => var2
[2] => var3
)
[photos] => Array (
[0] => var1
[1] => var2
)
)
Then you can do it like this (assuming this is PHP we are talking about):
$items = array( 'activity', 'photos');
$activity_subitems = array ('var1', 'var2', 'var3');
$photos_subitems = array ('var1', 'var2');
$query_vars = array();
foreach ($items as $item) {
$query_vars[$item] = ${$item.'_subitems'};
}
print_r($query_vars);
Also, keep in mind that the value names for the subarrays are generated from the values from the first array by appending _subitems to them.
I have renamed the variable $photo_subitems to $photos_subitems for this to work, because that is the value from the $items array.

Answer 2

I don't recognize the language, but in a pseudo-code kinda way
query_vars = new array();
for ($i in $items) {
for ($j in $i+'_subitems') {
query_vars.add($i, $j);
}
}
keeping in mind that you're creating the variable $j from from the value stored in $items (located # $j) and a static field _items

Answer 3

I am assuming you are working with PHP. First off, you will not be able to have multiple values with the same key in your array, but if you wish, you can make the values keyed to arrays themselves.
$items = array( 'activity', 'photos');
$activity_subitems = array ('var1', 'var2', 'var3');
$photo_subitems = array ('var1', 'var2');
$query_vars = array();
$query_vars['activity'] = $activity_subitems
$query_vars['photo'] = $photo_subitems
If you would like to have an array where the strings themselves start with photo/activity, but where it is not a dictionary (again, can't have duplicate keys), you can do something like the following:
NOTE: the eval() function is generally considered unsafe, and is not recommended for use in just about every language I know, and this is also true for PHP. Use the following at your own risk, but as long as you have strong control over what text can be placed into an eval() call (i.e., no user input is ever used), it should be somewhat safer. I get the impression you might want to use the values in $items to say what variable to use when building your result.
$items = array( 'activity', 'photos');
$activity_subitems = array ('var1', 'var2', 'var3');
$photos_subitems = array ('var1', 'var2');
$query_vars = array();
foreach ($items as &$item) {
foreach (eval('$'.$item.'_subitems') as &$subitem) {
$query_vars[] = $item.' =>'.$subitem;
}
}