If statement create array within an array

How if at all possible could an if statement add an array within an array.

example.

array(
  array(
    'name' => 'name',
    'type' => 'type',
    'label' => 'label',
  ),
  if( $a = $x ){
     array(
       'name' => 'name',
       'type' => 'type',
       'label' => 'label',
     ),
  }
  array(
    'name' => 'name',
    'type' => 'type',
    'label' => 'label',
  ),
)

I receive a parse error unexpected 'if' (T_IF), expecting ')'