How to generate multi-dimensional arrays from one-dimensional arrays

I have never quite understood how to quickly generate a multi-dimensional array from a one-dimensional array: I have a field that is a string and the value may be 1 or 1-2 or 1-2-3-4-5... for example, if it is 1-2-3-4, how can it generate a multi-dimensional array: {code ...} thank you for not understanding how to quickly generate a multi-dimensional array from a one-dimensional array:
I have a field that is a string and the value may be 1 or 1-2 or 1-2-3-4-5...

For example, if it is 1-2-3-4, how can we generate a multi-dimensional array:

Array(    [1] => Array        (            [2] => Array                (                    [3] => Array                        (                            [4] => Array                                (                                )                        )                )        ))

Thanks

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I have never understood how to quickly generate a multi-dimensional array from a one-dimensional array:
I have a field that is a string and the value may be 1 or 1-2 or 1-2-3-4-5...

For example, if it is 1-2-3-4, how can we generate a multi-dimensional array:

Array(    [1] => Array        (            [2] => Array                (                    [3] => Array                        (                            [4] => Array                                (                                )                        )                )        ))

Thanks

// from https://segmentfault.com/q/1010000004647414$str = '1-2-3-4';$arr = explode('-', $str);$last = null;while($last = array_pop($arr)) {    if(null != $last) {       array_push($arr,[array_pop($arr)=>$last]);    }    if(count($arr) <= 1) {        break;    } } print_r($arr[0]);/*Array(    [] => Array        (            [1] => Array                (                    [2] => Array                        (                            [3] => 4                        )                )        ))*/

Look at the matrix transpose function in the scientific computing package.