How replace number with "-" randomly from a range of number using php

This is my sample data. i want to replace 2 number from this range randomly.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,

i trying this code.

    <?php
    for ($i=1; $i <= $noof_q; $i++){
    for ($j=0; $j < $max_range; $j+=$increment){
    echo $min_range+$j.", ";
    }
    if ($j==$max_range) {
    echo "<br>";
    }
    }
   ?>