Twitchから情報を取得

http://checker-site.hatenablog.com/entry/2015/11/17/232409
↑これのphp版

<?php
date_default_timezone_set('Asia/Tokyo');
$url_base = 'https://api.twitch.tv/kraken/streams/';
$id_twitch = "riotgames"; //取得チャンネルのID
$twitch_url = $url_base . $id_twitch; 

$json = file_get_contents($twitch_url);
$arr = json_decode($json,true);

$isLive = $arr['stream']; //配信されていないならnull
$user_id = $arr['stream']['_id'];
$game = $arr['stream']['game'];
$viewers = $arr['stream']['viewers'];
$created_at = $arr['stream']['created_at'];
$preview_small = $arr['stream']['preview_small'];
$preview_medium = $arr['stream']['preview_medium'];
$preview_large = $arr['stream']['preview_large'];