Fastest way to return TRUE if all values in a 2d array column are numeric

Are there faster methods to check the existence of a number (not null) in one column of a multidimensional array in php (for instance, number9)?

Attempt:

The if statement below seems to be working okay.

$arr=Array(
    [0] => Array
        (
            [date] => 2019-01-16
            [number1] => 20.4
            [number2] => 20.54
            [number3] => 19.71
            [number4] => 19.73
            [number5] => 70849266
            [number6] => 70849266
            [number7] => -0.65
            [number8] => -3.189
            [number9] => 20.0902
            [string1] => Jan 16
            [number10] => 0.047796070100903
        )
    ... more rows ...
    [21] => Array
        (
            [date] => 2019-01-17
            [number1 => 19.49
            [number2] => 20.51
            [number3] => 19.02
            [number4] => 20.25
            [number5] => 85018421
            [number6] => 85018421
            [number7] => 0.52
            [number8] => 2.636
            [number9] => 19.7988
            [string1] => Jan 17
            [number10] => 0.075411577270313
        )
);


function isNumeric($var){
  if (is_numeric($var)){
    return true;
  } else {
    return false;
  }
}

if ((array_walk(array_column($arr, "number8"), 'isNumeric')) != 1)

Here are my ideas.
First is to just filter the array for numeric only values and compare to the original:

function with_array_filter($arr) {
    return $arr == array_filter($arr, 'is_numeric');
}

The second example uses casting to a float and then back to string, keep in mind that this is not going to be accurate for very big numbers, however seems to be the fastest (if you care about that at all):

function is_numeric_array_with_cast($arr) {
    foreach ($arr as $b) {
        if ($b != (string)(float)$b) {
            return false;
        }
    }
    return true;
}

However probably the simplest solution is to just foreach the array inside a function and return early:

function is_numeric_array_with_func($arr) {
    foreach ($arr as $b) {
        if (!is_numeric($b)) {
            return false;
        }
    }
    return true;
}

Benchmarked with an array of 20 elements over 100000 iterations on PHP 7.2:

$falseArray = [
    '1',
    2.5,
    -10,
    32,
    11.0,
    2.5,
    100101221,
    345,
    -10,
    '-10',
    '+10',
    '10',
    12,
    PHP_INT_MAX,
    PHP_INT_MAX + 1.4e5,
    '-10',
    null,
    'a',
    '5',
    5
];

Matt Fryer
Time: 4.8473789691925

is_numeric_array_with_func
Time:  4.0416791439056

is_numeric_array_with_cast
Time:  3.2953300476074

with_array_filter
Time:  3.99729180336