I have an array called $rows
. The first row is the header.
The first column is X
(input signal), the other columns are Y1
,Y2
,Y3
, etc. (output signals).
For any X
value some of Y
values may be NULL
.
I print it with this code:
$first_key = key($rows);
foreach ($rows as $key => $row) {
if($key == $first_key) { // print header
fputcsv($out, array_keys($row));
}
fputcsv($out, $row);
}
The output of this code look like this (sorted by X
column):
X | Y1 | Y2 | Y3 |
--------------------------
0.1 | | 10 | |
0.5 | 90 | | 7 |
0.7 | 15 | 40 | |
1.2 | | 12 | |
Goal: reorganize output to have columns X1
,Y1
,X2
,Y2
, etc such that in every pair (Xi
,Yi
) no NULL
(empty) values are in between the row data and the header:
X1 | Y1 | X2 | Y2 | X3 | Y3 |
------------------------------------------
0.5 | 90 | 0.1 | 10 | 0.5| 7 |
0.7 | 15 | 0.7 | 40 | | |
| | 1.2 | 12 | | |
My attempt:
$current_header = array_keys($rows[0]);
$size = count($current_header);
$new_header=array(); // the new header: X1, Y1, X2, Y2,...
$arr_X=array();
$arr_Y=array();
$x_column=$current_header[0];
for ($i=1; $i<$size; $i++) {
$y_column=$current_header[$i];
$new_header[2*$i] = $x_column;
$new_header[2*$i+1] = $y_column;
$arr_Y[$y_column] = array_column($rows, $y_column);
$arr_X[$y_column] = array_column($rows, $x_column);
}
Next step: join $arr_X[$y_column]
and $arr_Y[$y_column]
into arr_XY
. I think in this array the key should be the index (row#); also arr_XY
should not include the points where $arr_Y[$y_column]
is NULL
: I do not know how to do it
$arr_XY=array();
for ($i=1; $i<$size; $i++) {
$y_column=$current_header[$i];
// here should be the code to join arrays and eliminate NULL arr_Y points
$arr_XY[$y_column] = ($arr_X[$y_column], $arr_Y[$y_column]);
}
The final step is where I need help: build and print the output rows by combining all arr_XY[$y_column]
by row index.