Array to string conversion on array_map

I am utilizing array_map to kind out an array with all of my _octopud_id’s.

var_dump($workplaces): Returns the next:

array (dimension=500)
  0 => 
    array (dimension=1)
      'id' => string '1382' (size=4)
  1 => 
    array (dimension=1)
      'id' => string '1330' (size=4)

I have to enter that array integer into the ‘workers/’ part however I can not work out how – If I hardcode workers/6 I get the next consequence:

object(stdClass)[14592]
  public 'id' => int 6

What may I be doing fallacious? I hold getting the Discover: Array to string conversion error on the $outcomes = line.

/* Return an array of _octopus_ids */
$workplaces = array_map(
    operate($submit) {
        return array(
            'id' => get_post_meta($post->ID, '_octopus_id', true),
        );
    },
    $query->posts
);

var_dump($workplaces);

$outcomes = $octopus->get_all('worker/' . implode($workplaces));
var_dump($outcomes);