Convert Excel table to 2d array - php

Question

I have next Excel table with date in first column and some data in others (B, C).
1.
2.
And I want to transform it to table like on pic 3:
To do this you need to add up the data from each row and column within an hour (don't know how to say it right) and multiply by 2400.
For example, from first picture we have (0.0022 + 0.0078 + 0.0021 + 0.0078) * 2400 ≈ 47 — first element of the table from third picture.
I'm trying to do it with PHPExcel library:
$objPHPExcel = new PHPExcel();
$objPHPExcel = PHPExcel_IOFactory::load("data.xlsx");
$highestRow = $objPHPExcel->getActiveSheet()->getHighestRow();
$day = 1;
$hour = 1;
$data = array(array());
for ($i = 1; $i < $highestRow + 1; $i++) {
$cell1 = $objPHPExcel->getActiveSheet()->getCellByColumnAndRow(1, $i)->getValue();
$cell2 = $objPHPExcel->getActiveSheet()->getCellByColumnAndRow(2, $i)->getValue();
$data[$day][$hour] += $cell1 + $cell2;
if($i % 2 == 0) { $data[$day][$hour] *= 2400; $hour++; }
if($i % 48 == 0) $day++;
if($hour % 24 == 0) $hour = 1;
}
But instead of working code I get errors
Line 22:
$data[$day][$hour] += $cell1 + $cell2;
I think that something with my 2D array and as I can see my array keys is bad (not 1-24 for hours).
What should be the code to get my data in 2D array like $data[1..29-31][1-24] or any other? Or may be it is possible to get table from picture #3 some other way?

Answer 1

As your line number 22 is
$data[$day][$hour] += $cell1 + $cell2;
You are trying to increment $data[$day][$hour] which is not even defined yet. You need to define it before trying to increment it. I am not sure, it will make the sheet work like you are expecting. But this will fix the error you are getting. (Add this before line 22)
if(!isset($data[$day])) {
$data[$day] = array(); //Setting the day which will get the hours in array
}
if(!isset($data[$day][$hour])) {
$data[$day][$hour] = 0; //Setting the hours which will contain the incremented values for each hour. Setting it 0, the next code blocks will increment it.
}