compare.php

<?php

define('KEY_ID', 0);
define('KEY_DATE', 1);

/**
 * @param array $reports
 * @param string $start
 * @param string $end
 * @return array
 */
function timeFilter(array $reports, $start, $end)
{
    $start = strtotime($start);
    $end = strtotime($end);

    return array_filter($reports, function(array $report) use ($start, $end) {
        $current = strtotime($report[KEY_DATE]) ;

        return $start <= $current && $current < $end;
    });
}

$filepath = $argv[1];
$csv = array_filter(explode(PHP_EOL, file_get_contents($filepath)));
$reports = array_map('str_getcsv', $csv);

timeFilter($reports, '2015-01-02', '2015-01-05');