PHP使用地图数组？

I am new to php and trying to use map array. I would like my $arr2 to hold values of different types of fruits. But when I execute the following code, it tells me "apple" is an undefined index. Can you please show me how can I correct the following code so that I can accesses different values?

<?php
main_fun ();
function main_fun ()
{
    $arr2 = array();
    num2_data ($arr2); 

    echo "<br>.".$arr2["apple"]["q1"];    // quadrant 1 value of apple
    echo "<br>.".$arr2["orange"]["q2"];   // quadrant 2 value of orange      
}

function num2_data (&$arr2)
{       
    $arr2 = array("apple" => array("q1" => 1.1380711874577, "q2" => 1.7625118400083, "q3" => 1.8957417329238, "q4" => 2.4453545524829));        
    $arr2 = array("orange" => array("q1" => 1.1380711874577, "q2" => 2.5045795667914, "q3" => 1.8957417329238, "q4" => 2.7192512120757));
}   

?>

In your function, the second assignment to $arr2 is overwriting the previous (with apple)

To add an element, you can set it like this...

$arr2["orange"] = array("q1" => 1.1380711874577, "q2" => 2.50457956679 ...