基于var的PHP填充数组

I feel like I'm struggling to find the answer here because I think I'm missing some key piece of info.

What I am trying to do is run a loop over some data, and then do something different with it based on one of it's values.

So the print_r of the data I am looping over gives me this. This is all good, it has only the data I need, nothing excess.

Array
(
[foodid] => 1
[menuid] => 1789798798
[creatorid] => 1
[foodtype] => hotdog
[frequency] => weekly
[cost] => 20
[chargedate] => 2017-07-14 11:05:18
)

And I want to do SOMETHING to it, depending on the value in frequency. The things I want to do are all stored in a set of identical arrays.

weekly, 2weekly, monthly, daily. eg

$_weekly = array(
"cost" => "2",
"order" => "5",
"years" => "0",
);

$_2weekly = array(
"cost" => "4",
"order" => "10",
"years" => "0",
);

Similar arrays for weekly 2weekly etc.

It seems simple to just use a var like $workingvar in the loop. So when I get there I can just use $workingvar = $_weekly, or $workingvar = $_2weekly.

So, how can I set the contents of $workingvar to be one of those existing arrays? Then I can use the same loop/function on each row in the data, and change the values it pulls in, depending on what that frequency value contains.

Edit added second array example.

So you need variable variable, in your case it is:

$arr['frequency'] = 'weekly';
$_weekly = [11,22,33];

$workingvar = ${'_' . $arr['frequency']};
var_dump($workingvar);

But having array with same keys is a more preferred solution (simply because it's more readable and shorter):

$arr['frequency'] = 'weekly';
$arrs = [
    'weekly' => [11,22,33],
];
var_dump($arrs[$arr['frequency']]);

There are many ways to achieve this. If you can guarantee frequency to always have a valid value, then a global look-up array like this could do:

// Define your $_weekly, $_2weekly, etc here

$freqLookup = array(
    "weekly" => $_weekly,
    "2weekly" => $_2weekly,
    // et cetera
  );

Then in your code you simply assign to $workingvar:

$workingvar = $freqLookup[$data["frequency"]];

If you cannot guarantee frequency to always have a valid value, then you can check that the key exists first:

if (!isset($freqLookup[$data["frequency"]])) {
  // Throw an exception or do something to handle the error
}

A possible alternative (but less elegant) solution is a switch, and even less elegant is an if ... else if ... else chain. They could have their merits if you needed to do something very different for each case.

Edit: u_mulder's answer is probably even better IF you can guarantee the sanity of your data. If you are accepting user data, it could be dangerous. Another advantage to a lookup array is that you could map keys to different variables, e.g. "2weekly" => $_biweekly