How to match array_intersect() values to corresponding key in another array?

Question

Lets say this is my sql database column values:

Result  -      Reference

  1                A1
  2                A2
  3                A3
  4                A4
  5                A5

After fetching the above columns, I have the following arrays:

$inputValue = array(1,3,5);  //This is the User Input

$result = array(1,2,3,4,5); //This is the mysql fetched result of 'Results' column

$reference = array('A1','A2','A3','A4','A5'); //This is the fetched result of 'Reference' column

$filteredData = array_intersect($inputValue, $result);

print_r($filteredData);

When I do array_intersect($inputValue, $result); this gives the output:

Array ( [0] => 1 
    [1] => 3 
    [2] => 5 )

Now after the array_intersect, how will I store the corresponding references into another array? Meaning, after the intersect, the $filteredData has the array values 1,3,5. Now I also want the corresponding references to be stored in a separate array which should have this value: $MatchingReference = array(A1,A3,A5);

How is this done?

Xardas · Accepted Answer · 2014-01-17 22:12:41Z

2

I would try this:

$filteredReferences = array();
foreach($filteredData as $key) {
    $filteredReferences[] = $reference[$key-1];
}

edited Jan 17, 2014 at 22:12

answered Jan 17, 2014 at 22:00

Xardas

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4 Comments

Neel Over a year ago

I like your suggestion. But when I tried that, I am getting: Notice: Undefined offset: 5 in C:\Users\test.php on line 18 Array ( [0] => A2 [1] => A4 [2] => ). My line 18 is $filteredReferences[] = $reference[$key];

Bill Karwin Over a year ago

Remember that array indexes start at zero, not 1.

Neel Over a year ago

Just 1 typo. You need to add the semi-colon (;) at the end of 1st line. Tried editing it but it says edit needs to be atleast 6 characters. Cheers.

Neel Over a year ago

Hi Xardas, I did a few testing, but I think @BillKarwin approach is probably better. Your code works well with the example I had given where the array values are in order like 1,2,3,etc.. But if I have $inputValue as say '1,58,51' and $result array value as '1,2,58,4,51', then I will get an error since it is looking for $reference[$key-1].

Bill Karwin · Accepted Answer · 2014-01-17 22:05:22Z

1

Combine the two arrays from the database into an associative array. Then use the user input to select only a subset of keys.

$filteredData = array_intersect_key(
    array_combine($result, $reference), 
    array_flip($inputValue)
);

answered Jan 17, 2014 at 22:05

Bill Karwin

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2 Comments

Neel Over a year ago

Your method works too. Both yours and Xardas suggestion does exactly what I wanted!. Fantastic :)

Neel Over a year ago

After a few testing, I think your method is the best approach. I had added my reason in the comment under @Xardas suggested answer. :) Thank you Bill.

mickmackusa · Accepted Answer · 2022-04-03 05:21:02Z

1

If this was a task in my own application, I would definitely implement the data filter with SQL instead of PHP.

Otherwise, you going to need perform a few manipulations to enjoy efficient key-based filtration and reach your desired output. (Demo)

var_export(
    array_intersect_key(
        array_column($resultSet, 'reference', 'result'),
        array_flip($inputValue)
    )
);

edited Apr 3, 2022 at 5:21

answered Feb 22, 2022 at 14:09

mickmackusa♦

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1 Comment

Neel Over a year ago

Thank you @mickmackusa I am about to update the codes in my app this year as an upgrade process and I will review the above code and try your recommendation. thank you for sharing your suggestion.

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