Question

Consider the following data.csv:

 "1", "2", "3", "4"
 "5", "6", "7", "8"
 "9","10","11","12"
"13","14","15","16"
"17","18","19","20"
"21","22","23","24"
"25","26","27","28"
"29","30","31","32"
"33","34","35","36"

In reality, the rows and columns are much longer, but the principle stays the same.

I need a way to read the csv file, remove the quotes and concatenate every 3 consecutive rows to each other to format the following output:

1,2,3,4,5,6,7,8,9,10,11,12
13,14,15,16,17,18,19,20,21,22,23,24
25,26,27,28,29,30,31,32,33,34,35,36

I now have:

$path = "data.csv";
$row = 0;
$newrow = 0;
$newrows = array();
if (($handle = fopen($path, "r")) !== FALSE) {
  while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
    $newrows[$newrow] = implode("," $data);
    if ($row % 3) $newrow++;
    $row++;
  }
  fclose($handle);
}

What I’m trying to do is create an array “newrows” (see below) in which data is added to the current new row while $row cannot be devided by 3

$newrows = array (
  [0] = "1,2,3,4,5,6,7,8,9,10,11,12",
  [1] = "13,14,15,16,17,18,19,20,21,22,23,24",
  [2] = "25,26,27,28,29,30,31,32,33,34,35,36"
)

My code obviously isn’t working, but I am confused as how to proceed. Do you know? Any help is greatly appreciated 🙂

edit I seem to have made a mistake. The output should not be “concatenate every set of 3 rows” but rather “concatenate every third row”, so:

• every 3rd row is concatenated to the previous 3rd one
• row 4 (1 + 3) and 7 (1 + 3 + 3) are concatenated to row 1
• row 5 (2 + 3) and 8 (2 + 3 + 3) are concatenated to row 2
• row 6 (3 + 3) and 9 (3 + 3 + 3) are concatenated to row 3

The output then would be an array:

array (
  [0] => 1,2,3,4,13,14,15,16,25,26,27,28
  [1] => 5,6,7,8,17,18,19,20,29,30,31,32
  [2] => 9,10,11,12,21,22,23,24,33,34,35,36
)

I tried this but it concatenates incorrect:

$path = "data.csv";
$row = 1;
if (($handle = fopen($path, "r")) !== FALSE) {
  while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
    for ($i = 1; $i <= 3; $i++) {
      if ($row % $i == 0) $newrows[$i] .= implode(",", $data);
    }
    $row++;
  }
}

print_r($newrows);

Array (
  [1] => 1,2,3,45,6,7,89,10,11,1213,14,15,1617,18,19,2021,22,23,2425,26,27,2829,30,31,3233,34,35,36
  [2] => 5,6,7,813,14,15,1621,22,23,2429,30,31,32
  [3] => 9,10,11,1221,22,23,2433,34,35,36
)

P.S. In reality, the csv is much larger and I need every 147th row to be concatenated to the previous 147th row, but the principle is the same I guess.

Answer 1

Your while loop needs some work:

$newrow = 0; $row = 1;
while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) {
    if( !isset( $newrows[$newrow])) $newrows[$newrow] = '';
    $newrows[$newrow] .= implode(",", $data);
    if ($row % 3 == 0) {
        $newrow++;
    } else {
        $newrows[$newrow] .= ', ';
    }
    $row++;
}

Notable changes:

• $row now starts at 1, so the first three iterations will be mapped to the same entry.
• $newrows[$newrow] = ''; is properly initialized.
• $row % 3 is compared to == 0, which determines if we’re at the end of every third row correctly.
• $newrows[$newrow] is set to .= implode(",", $data);, which will continually concatenate rows together. Otherwise, only the last iteration would be kept in your original code.