Specifying object in PHP Array from JSON

Question

I'm trying to use a specific object type from a JSON feed, and am having a hard time specifying it. Using the code below I grab and print the specific array (max) I want,

$jsonurl = "LINK";
$json = file_get_contents($jsonurl,0,null,null);
$json_output = json_decode($json,true);
$max_output = $json_output["max"];

echo '<pre>';
print_r($max_output);
echo '</pre>';

And from the Array below, all I want to work with is the [1] objects in each array. How can I specify and get just those values?

Array
(
[0] => Array
    (
        [0] => 1309924800000
        [1] => 28877
    )

[1] => Array
    (
        [0] => 1310011200000
        [1] => 29807
    )

[2] => Array
    (
        [0] => 1310097600000
        [1] => 33345
    )

[3] => Array
    (
        [0] => 1310184000000
        [1] => 33345
    )

[4] => Array
    (
        [0] => 1310270400000
        [1] => 33345
    )

[5] => Array
    (
        [0] => 1310356800000
        [1] => 40703
    )

possible duplicate of Is there a function to extract a 'column' from an array in PHP? — Felix Kling
– Felix Kling, Commented Feb 14, 2012 at 18:59

vstm · Accepted Answer · 2012-02-14 18:53:58Z

1

Well you could fetch those values with array_map:

$max_output = array_map(function($val) { return $val[1]; }, $json_output["max"]);

This requires PHP 5.3, if you use an earlier version, then you can use create_function to achieve similar results:

$max_output = array_map(create_function('$val', 'return $val[1];'), $json_output["max"]);

answered Feb 14, 2012 at 18:53

vstm

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4 Comments

user895378 Over a year ago

+1 for array_map, which, IMHO, is a more semantically appropriate solution than looping. It's worth noting that when I've benchmarked array_map vs. foreach performance on controlled tasks the loop is usually a fair amount faster than the array_map call. This is anecdotal evidence, though, so take it with a grain of salt and run your own benchmarks for oft-executed code blocks.

zamo.tox Over a year ago

This did exactly what I needed. Now $max_output shows only the objects I wanted. Huge thanks!

user895378 Over a year ago

@user1209756 Then you should accept the answer! (click the checkbox and make it green)

vstm Over a year ago

@rdlowrey: thank you very much for the comment. A quick google-session turns out that there are other benchmarks which support your point. I guess if the input size is large enough it's definitely better to use foreach. But for small arrays it's just a matter of taste (meaning, the difference won't be significant).

Vyktor · Accepted Answer · 2012-02-14 19:05:13Z

1

When you need to create new array which will contain only second values, you may use either foreach loop which will create it or use array_map() (just for fun with anonymous function available since php 5.3.0):

$newArray = array_map( function( $item){
    return $item[1]
},$array);

Then you want to use last ("max" -> considering array with numeric keys) item, you can use end():

return end( $item);

And when you can process your data sequentially (eg. it's not part of some big getData() function) you can rather use foreach:

foreach( $items as $key => $val){
    echo $val[1] . " is my number\n";
}

answered Feb 14, 2012 at 19:05

Vyktor

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Comments

kitti · Accepted Answer · 2012-02-14 18:52:52Z

0

After you get $max_output...

for( $i = 0; $i < length( $max_output ); $i++ ) {
    $max_output[$i] = $max_output[$i][1];
}

answered Feb 14, 2012 at 18:52

kitti

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Comments

Mikhail · Accepted Answer · 2012-02-14 18:53:44Z

0

try this:

$ones = array();
foreach ($max_output as $r)
    $ones[] = $r[1];

answered Feb 14, 2012 at 18:53

Mikhail

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