Refactoring PHP code - reducing number of foreach statements

Question

as you can see in my code below, I'm using the same code (foreach loop with array assignment and trailing json_decode) three times for three variables that are structured similarly. I'm wondering how I can optimize my code so that it doesn't repeat functions unnecessarily. Would variable variables be helpful in this situation? Can I move the recurring lines of code to inside the first foreach statement?

Here's what my code looks like now:

date_default_timezone_set('America/Los_Angeles');

$stocks = array('MSFT' => 'http://ichart.finance.yahoo.com/table.csv?s=MSFT', 'AAPL' => 'http://ichart.finance.yahoo.com/table.csv?s=AAPL', 'FB' => 'http://ichart.finance.yahoo.com/table.csv?s=FB', 'ZNGA' => 'http://ichart.finance.yahoo.com/table.csv?s=ZNGA');

foreach ($stocks as $key=>$stock) {
    $fh = fopen($stock, 'r');
    $header = fgetcsv($fh);

    $varname = $key . '_data';

    $$varname  = array();
    while ($line = fgetcsv($fh)) {
        ${$varname}[count($$varname)] = array_combine($header, $line);
    }

    fclose($fh);
}

foreach($MSFT_data as $val){
    $MSFT[] = array((strtotime($val['Date']) * 1000), ((float)$val['Close']));
}
$MSFT = json_encode(array_reverse($MSFT));

foreach($AAPL_data as $val){
    $AAPL[] = array((strtotime($val['Date']) * 1000), ((float)$val['Close']));
}
$AAPL = json_encode(array_reverse($AAPL));

foreach($FB_data as $val){
    $FB[] = array((strtotime($val['Date']) * 1000), ((float)$val['Close']));
}
$FB = json_encode(array_reverse($FB));

Thanks. Let me know if you have any questions.

Why are you creating variable names dynamically but not just use an associative array? — Alvin Wong
– Alvin Wong, Commented Mar 11, 2013 at 2:51
This is a question I've been wondering for long enough, how to do a foreach loop for more than 1 array with the same number of elements and for each of them at the same time. — Francisco Presencia
– Francisco Presencia, Commented Mar 11, 2013 at 3:08

Tigger · Accepted Answer · 2013-03-11 03:05:47Z

1

For the three loops, try:

function dateCloseLoop($data) {
    foreach($data as $val){
        $tmp[] = array((strtotime($val['Date']) * 1000), ((float)$val['Close']));
    }
    return json_encode(array_reverse($tmp));
}

So your code would be something like:

$MSFT = dateCloseLoop($MSFT_data);
$AAPL = dateCloseLoop($AAPL_data);
$FB = dateCloseLoop($FB_data);

answered Mar 11, 2013 at 3:05

Tigger

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fuzic · Accepted Answer · 2013-03-11 02:55:06Z

1

You could just use an associative array, storing a data array for each stock key, and use nested foreach's on that nested array.

Something like this:

$res = array();
$stocks = array('MSFT' => '...', 'AAPL' => '...', 'FB' => '...', 'ZNGA' => '...');

foreach ($stocks as $stock => $url) {
    $fh = fopen($url, 'r');
    $header = fgetcsv($fh);

    $res[$stock] = array();

    while ($line = fgetcsv($fh)) {
        $res[$stock][] = array_combine($header, $line);
    }

    fclose($fh);
}

$json = array();

foreach ($res as $stock => $data) {
    $out = array();
    foreach($data as $val){
        $out[] = array((strtotime($val['Date']) * 1000), ((float)$val['Close']));
    }
    $json[$stock] = json_encode(array_reverse($out));
}

answered Mar 11, 2013 at 2:55

fuzic

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3 Comments

conbask Over a year ago

I like the idea of this solution because it would be easy to add data just by adding an item to the $stocks array, but when I tried this code (added in URLs too) it did not work.

fuzic Over a year ago

Which part didn't work? Is it not the output format you're looking for, or did it throw an error? It's working on my local setup.

conbask Over a year ago

I'm using the data in a Highcharts (jQuery data visualization plugin) implementation and for some reason the arrays aren't being passed into my JS.

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