How can I use a php array as a path to target a value in another array?

Question

I want to access a specific array's property by using a separate array as the path. The problem is the property in question may be at any depth. Here's an example...

I have the associative array of data:

$data = array(
    '1' => 'somethings_value',

    '2' => 'another_value',

    '3' => array(
        '1' => 'deeper_value',
    ),
);

Now I want to access one of these values but using another array that will dictate the path to them (through the keys). So say I had a path array like this:

$path = array('3', '1');

Using that $path array I would want to get to the value $data[3][1] (which would be the string 'deeper_value').

The problem is that the value to access may be at any depth, for example I could also get a path array like this:

$path = array('1');

Which would get the string value 'somethings_value'. I hope the problem is clear now.

So the question is, how do I somehow loop though this path array in order to use its values as keys to target a value located in a target array?

Thanks!

EDIT: It might be worth noting that I have used numbers (albeit in quotes) as the keys for the data array for ease of reading, but the keys in my real problem are actually strings.

Community · Accepted Answer · 2017-05-23 11:55:53Z

4

A simple loop should work:

Update: sorry did check my code

foreach($path as $id) 
{
    $data = $data[$id];
}

echo $data;

Result:

deeper_value

This will overwrite the $data array so you might want to make a copy of $data first like David did in his example.

edited May 23, 2017 at 11:55

CommunityBot

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answered Jul 8, 2011 at 14:28

Glass Robot

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4 Comments

David Amey Over a year ago

You wouldn't be able to access $data[3][1] with this method.

SteeveDroz Over a year ago

I'm not sure of what I'm about to say, but are you sure that foreach will always take the $id in the correct order? That's not the case in Java, for example.

grossvogel Over a year ago

@Oltarus: I'm sure that php's arrays always have a well-defined order that foreach respects, and that the order defaults to the order of insertion... but I can't find a reference!

SteeveDroz Over a year ago

@grossvogel Ok, Big Bird, just checking!

David Amey · Accepted Answer · 2011-07-12 08:24:47Z

3

It's not the greatest code, but should work:

function getValue($pathArray, $data)
{
   $p = $data;
   foreach ($pathArray as $i)
   {
     $p = $p[$i];
   }

   return $p;
}

edited Jul 12, 2011 at 8:24

answered Jul 8, 2011 at 14:26

David Amey

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1 Comment

grossvogel Over a year ago

You can't access $data inside a function unless you use the global keyword. Since global is lame, you should pass $data as a function parameter, which also saves you from having to explicitly create a copy.

Sascha Galley · Accepted Answer · 2011-07-08 14:42:45Z

0

Here is a different approach:

while($d = array_shift($path))
    $data = $data[$d];

answered Jul 8, 2011 at 14:42

Sascha Galley

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