Extract data using index, not name - php

Question

I am parsing a csv file, and then looping it like so.
foreach ($this->csvData as $dataKey => &$item) {
foreach ($item as $key => $value) {
print_r($item);
}
}
Now if I output item, I can see something like the following
array:12 [
"ID" => "12345"
"CODE" => "AZ6G"
"YEAR" => "2009"
"WEEK" => "13"
"FULL_DATE" => "29/04/2014"
"SALES" => "asdas89.34"
"QUANTITY" => "3"
]
So the above example represents one row in the csv, the key is the header name and then it has a value.
The problem is this, I know which columns I need to keep based on an index value. These values are selected by the user at a previous stage. So in the above example I know I need to keep the ID, FULL_DATE and SALES, so in my database I have 0, 4, 5 which represents their indexes.
Now I need to extract these columns. If I do something like the following
foreach ($this->csvData as $dataKey => &$item) {
foreach ($item as $key => $value) {
print_r($item[4]);
}
}
I will get an undefined index problem as there is no key named 4. If I give it the name of the key, it will work, and show me the value.
So how can I get the value using the key index instead of the name?
Thanks

Answer 1

you could use array_keys and then loop over those keys you said you get from the Database like so:
<?php
$keys = [0, 4, 5];
$data = [
"ID" => "12345",
"CODE" => "AZ6G",
"YEAR" => "2009",
"WEEK" => "13",
"FULL_DATE" => "29/04/2014",
"SALES" => "asdas89.34",
"QUANTITY" => "3"
];
foreach($keys as $key) {
echo $data[array_keys($data)[$key]] . "\n";
}
// outputs:
// 12345
// 29/04/2014
// asdas89.34
Explanation what happens:
array_keys($data)[0]; // is "ID"
// and the "ID" can be used as "key" for the $data array with
$data[array_keys($data)[0]]; // which is $data["ID"]; => "12345"
You can play with it online here: http://sandbox.onlinephpfunctions.com/code/4d6a4d86a6cdceccf4034fca06dcef9e50a89dc8