Removing Weekends From Array - php

Question

I have a JSON of all bitcoin prices for previous 90 days. I'm trying to only work with the weekday prices, excluding weekend prices. This is how I am doing it. Could you please tell me what I'm doing wrong or point me in the right direction?
<?php
$string = file_get_contents("https://blockchain.info/charts/market-price?timespan=90days&format=json");
$btc_price = json_decode($string, true);
$allDays = $btc_price[values];
$weekends = array_filter($allDays[values][x], function($d) {
return (date('N', strtotime(date("Y-m-$d"))) >= 6);
});
$allDays[$year][$month] = array_diff($allDays[$year][$month], $weekends);
echo "<pre>";
print_r($allDays);
?>

Answer 1

You're fairly close. I've made a few changes to get it working:
Instead of passing in $allDays['values']['x'], you should pass in all of the days. This will allow you to remove each weekend day without having to do the array_diff step. $allDays['values']['x'] should be $allDays.
Your expression in the array_filter callable was wrong. I'm not clear what your intention was, but it looks like you were attempting to get the day of the week and filter on that. That's a good strategy, but your implementation wasn't effective. You can get the day of the week with w in date and pass in the unix timestamp you were given from the API. Also, checking for greater than 6 wasn't effective, since Sunday is 0.
$weekends = array_filter($allDays[values][x], function($d) {
return (date('N', strtotime(date("Y-m-$d"))) >= 6);
});
should be changed to:
$allDays = array_filter($allDays, function($d) {
return !(date('w', $d['x']) == 6 || date('w', $d['x']) == 0);
});
I've cleaned up some syntax. When accessing array keys, you should wrap your indexes in quotes. PHP was trying to interupt your keys as constants before falling back to the expected behavior. $allDays[values][x] should have been $allDays['values']['x'].
Here's the full snippet so you have context:
<?php
$string = file_get_contents("https://blockchain.info/charts/market-price?timespan=90days&format=json");
$btc_price = json_decode($string, true);
$allDays = $btc_price['values'];
$allDays = array_filter($allDays, function($d) {
return !(date('w', $d['x']) == 6 || date('w', $d['x']) == 0);
});
// This is just done to reset the keys in the array. It's entirely optional.
$allDays = array_values($allDays);
echo "<pre>";
print_r($allDays);
?>