Unexpected 'if' inside array. Laravel

I'm trying to filter values that will be inside array. For that I used following syntax: $selected = array(

    if ($request->annual!=0) {
        'annual' => $request->annual,
    }
    if ($request->registration!=0) {
        'registration' => $request->registration,
    }
    if ($request->monthly!=0) {
        'monthly' => $request->registration,
    }
    if ($request->exam!=0) {
        'exam' => $request->exam,
    }
    if ($request->laboratory!=0) {
        'laboratory' => $request->laboratory,
    }
    if ($request->computer_lab!=0) {
        'computer_lab' => $request->computer_lab,
    }  
);

But it is throwing syntax error.

syntax error, unexpected 'if' (T_IF), expecting ')'

What is the problem here? Can anyone help me?