PHP按列解析CSV

I would like to ask for help with this task: I have CSV for example like this:

column1$column2$column3
123$xyz$321
456$zyx$654

And I would like to parse it by PHP to Arrays by columns / headers -> for example

$column1 = {123,456}
$column2 = {xyz,zyx}
$column3 = {321,654}

Thanks everyone.

Consider the following code and explanations:

$file = file("example.csv");              // read the file to an array
$cols = array();
for ($i=1;$i<count($file);$i++) {         // loop over $file, 
                                          // starting in the second line
    $row = explode('$', $file[$i]);       // make an array with explode
    for ($j=0;$j<count($row);$j++)        // loop over the $row array
        array_push($cols["column".$j], $row[$j]);
                                          // push it to the cols array
}
print_r($cols);

What are your curly brackets supposed to do? In PHP an array is formed with [].
Rather than reading the whole file to an array you could as well read each line and push it to the cols array.