php array and foreach / array unique / array push key=> value

Question

I have a loop in php that returns this result :

• name 1 => value x
• name 2 => value y
• name 3 => value x
• name 1 => value y
• name 2 => value y

I want to create an array like this :

$myarray=array('name 1' =>'value x, value y','name 2'=>'value y',name 3=>'value x')

So with this array, I can manipulate it like this :

foreach($myarray as $key=>$item){
    echo $key.'=>'.$item;
}

The result:

• name 1 => value x,value y
• name 2 => value y
• name 3 => value x

How can I do this?

Answer 1

It looks awful because php doesn't have native lists. You shouldn't use a hashmap (associative array) when the keys can be the same. I haven't tested the following but something like this:

<?
$arr = Array(
Array('n1',Array('x','y'))
, Array('n2',Array('x'))
, Array('n3',Array('y'))
);

foreach($arr as $value){
list($name,$values) = $value;
foreach($values as $value){
echo "$name -> $value".PHP_EOL;
}
}
?>

Answer 2

Create an empty array for the output, then for each input value check to see if the key already exists.

$result = array();

foreach($myarray AS $key=>$value) {
    if(array_key_exists($key, $result)) {
        // if the key exists in $result, add the value to the existing value
        $result[$key] += ', ' + $value;
    } else {
        // otherwise, just create it
        $result[$key] = $value;
    }
}

Answer 3

$array2 = array();
foreach ( $original_array as $key => $value )
{
  // Edited to address @adam's comment
  if ( !array_key_exists( $key, $array2 ) ) $array2[$key] = array();
  $array2[$key][] = $value;
}

foreach ( $array2 as $key => $values )
{
  $values_str = join( ', ', array_unique( $values ) );
  print "$key => $values_str";
}