I have the following two-dimensional array:
01 03 02 15
05 04 06 10
07 09 08 11
12 14 13 16
I want to convert columns to rows then reduce the matrix to a string like the following:
01,05,07,12|03,04,09,14|02,06,08,13|15,10,11,16
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5 Answers
I'm assuming that you have this array:
$array = array (
array ('01','03','02','15'),
array ('05','04','06','10'),
array ('07','09','08','11'),
array ('12','14','13','16')
);
In which case, you can do this:
$tmpArr = array();
foreach ($array as $sub) {
$tmpArr[] = implode(',', $sub);
}
$result = implode('|', $tmpArr);
echo $result;
1 Comment
mickmackusa
This answer is provably incorrect because it does not transpose the data. Proof
$input = array(
array('01', '02', '03', '04'),
array('11', '12', '13', '14'),
array('21', '22', '23', '24'),
array('31', '32', '33', '34'),
);
$newArray = array();
foreach($input as $rowIndex => $row) {
foreach($row as $key => $val) {
if(!$newArray[$key]) {
$newArray[$key] = array();
}
$newArray[$key][$rowIndex] = $val;
}
}
$strRows = array();
foreach($newArray as $key => $row) {
$strRows[$key] = join(',', $row);
}
$output = join('|', $strRows);
1 Comment
mickmackusa
This answer generates multiple undefined array key Warnings. Proof
The most elegant script for this "transpose and double-implode" task is to call array_map() with a spread operator on the input array, then join the columns with commas, the join the joined strings with pipes.
Code: (Demo)
var_export(
implode(
'|',
array_map(
fn() => implode(',', func_get_args()),
...$input
)
)
);
Or collect all of the column data in the function signature. (Demo)
var_export(
implode(
'|',
array_map(
fn(...$column) => implode(',', $column),
...$input
)
)
);
For similar questions that do not require a single string of output, but prefer an array of delimited strings, simply remove the outer implode() call. Namely:
Comments
Given your array as $myArray, like this:
$newArray = array();
foreach ($myArray as $row) {
$rowValue = implode(',', $row);
$newArray[] = $rowValue;
}
$finalString = implode('|', $newArray);
1 Comment
mickmackusa
This answer is provably incorrect because it does not transpose the data. Proof
Looking at the solutions proposed so far, only one actually generates the correct output requested by the OP.
So, stealing unashamedly from salathe's neat conversion, but with a transpose to provide the correct result:
$input = array (
array ('01','03','02','15'),
array ('05','04','06','10'),
array ('07','09','08','11'),
array ('12','14','13','16'),
);
function transpose($array) {
array_unshift($array, null);
return call_user_func_array('array_map', $array);
}
$transposed = transpose($input);
echo implode('|', array_map('implode', $transposed, array_fill(0, count($transposed), ',')));
1 Comment
mickmackusa
While this answer DOES transpose the array data; as of PHP8 its implementation of implode() causes a Fatal error. Proof