Question

I have an array that is taken from an image using

exif_read_data($image, 0, true)

The array itself can contain an unknown number of keys/values (can also be 0)
The array is also Multidimentional in some parts.

An example of an array from exif_read_data :

Array
(
    [FILE] => Array
        (
            [FileName] => f-20110129_004_pp.jpg
            [FileDateTime] => 0
            [FileSize] => 3566966
            [FileType] => 2
            [MimeType] => image/jpeg
            [SectionsFound] => ANY_TAG, IFD0, THUMBNAIL, EXIF, GPS
        )

    [COMPUTED] => Array
        (
            [html] => width="2576" height="1936"
            [Height] => 1936
            [Width] => 2576
            [IsColor] => 1
            [ByteOrderMotorola] => 0
            [ApertureFNumber] => f/2.8
            [Thumbnail.FileType] => 2
            [Thumbnail.MimeType] => image/jpeg
        )

    [IFD0] => Array
        (
            [ImageWidth] => 2576
            [ImageLength] => 1936
            [BitsPerSample] => Array
                (
                    [0] => 8
                    [1] => 8
                    [2] => 8
                )

            [Make] => Nokia
            [Model] => N900
            [Orientation] => 1
            [SamplesPerPixel] => 3
            [XResolution] => 3000000/10000
            [YResolution] => 3000000/10000
            [ResolutionUnit] => 2
            [Software] => Adobe Photoshop CS5 Windows
            [DateTime] => 2011:01:29 09:37:30
            [YCbCrPositioning] => 1
            [Exif_IFD_Pointer] => 276
            [GPS_IFD_Pointer] => 658
        )

    [THUMBNAIL] => Array
        (
            [Compression] => 6
            [XResolution] => 72/1
            [YResolution] => 72/1
            [ResolutionUnit] => 2
            [JPEGInterchangeFormat] => 978
            [JPEGInterchangeFormatLength] => 5525
        )

    [EXIF] => Array
        (
            [ExposureTime] => 1/500
            [FNumber] => 14/5
            [ExposureProgram] => 0
            [ISOSpeedRatings] => 100
            [ExifVersion] => 0210
            [DateTimeOriginal] => 2011:01:29 09:37:30
            [DateTimeDigitized] => 2011:01:29 09:37:30
            [ShutterSpeedValue] => 8/1
            [ApertureValue] => 297/100
            [LightSource] => 0
            [Flash] => 0
            [FocalLength] => 26/5
            [FlashPixVersion] => 0100
            [ColorSpace] => 1
            [ExifImageWidth] => 2576
            [ExifImageLength] => 1936
            [CustomRendered] => 0
            [ExposureMode] => 0
            [WhiteBalance] => 0
            [DigitalZoomRatio] => 1/1
            [SceneCaptureType] => 0
            [GainControl] => 0
            [Contrast] => 0
            [Saturation] => 0
        )

    [GPS] => Array
        (
            [GPSVersion] => 
            [GPSLatitudeRef] => N
            [GPSLatitude] => Array
                (
                    [0] => 22/1
                    [1] => 12937/1000
                    [2] => 0/1
                )

            [GPSLongitudeRef] => E
            [GPSLongitude] => Array
                (
                    [0] => 113/1
                    [1] => 32886/1000
                    [2] => 0/1
                )

            [GPSAltitudeRef] => 
            [GPSAltitude] => 255/1
            [GPSTimeStamp] => Array
                (
                    [0] => 9/1
                    [1] => 37/1
                    [2] => 30/1
                )

            [GPSMapDatum] => WGS-84
            [GPSDateStamp] => 2011:01:29
        )

)

My question is how can I create a function that will display only the keys that I select , as a key/value pair , even if it is in the 2nd, or 3rd dimension of the array?

for example – from the array above , if I want to select only the [ImageWidth] , [ImageLength] , [XResolution] , [GPSTimeStamp] and [GPSLatitude] ..

I would pass it to the function like :

$keys_array = (ImageWidth , ImageLength, XResolution, GPSTimeStamp , GPSLatitude) 

and then

function select_keys_from_array ($keys_array='') {  
// if $keys_array=='' then get all ..
//identify the dimension or flatten - and get only my keys and display key/value 
}

I have selected those keys as example because some of them are on a second-level, and some are actually arrays themselves ..

There is also a problem is that the keys can theoretically be duplicated (user-keys) – but residing in different second-level array (and therefor not nominally duplicated.)

I guess I will need to “flatten” it first , and then to “pass” an array of my wanted keys somehow – but I can not really seem to get it right .

Does someone knows any ready-made class / function / snippet for that sort of thing ?

Answer 1

_{(Disclaimer; may do wacky stuff, not fully tested — should be fine though)}

Last edit; the first one was better, as it didn’t exclude array values (such as coordinates, etc.)

function array_by_keys_recursive(array $keys, array $array) {
    $results = array();
    foreach ($keys as $key) {
        if (isset($array[$key])) {
            $results[$key] = $array[$key];
            continue;
        }
        foreach ($array as $value) {
            if (\is_array($value)) {
                $results = \array_replace($results,
                    \array_by_keys_recursive(array($search), $value));
            }
        }
    }
    return $results;
}

Test:

$array = array(
    'a' => 1,
    'b' => 2,
    'c' => array(
        'd' => 3,
        'e' => 4,
    ),
    'f' => 5,
    'g' => array(
        'h' => array(
            'i' => 6,
            'j' => 7,
        ),
        'k' => 8,
    ),
);

\var_dump(\array_by_keys_recursive(array('a', 'b', 'c', 'h', 'i', 'j'), $array));

Results:

array(6) {
  ["a"]=>
  int(1)
  ["b"]=>
  int(2)
  ["c"]=>
  array(2) {
    ["d"]=>
    int(3)
    ["e"]=>
    int(4)
  }
  ["h"]=>
  array(2) {
    ["i"]=>
    int(6)
    ["j"]=>
    int(7)
  }
  ["i"]=>
  int(6)
  ["j"]=>
  int(7)
}