Question

I am currently using fgetcsv in php to get rows in CSV file. For each row, I need it’s 3 previous rows and 3 next rows for some requirement.

while(($data = fgetcsv($handle, 5000, ",")) !== FALSE) {
    //$data is current row data
    //I need previous rows and next rows data
}

I don’t know how to try this, as each while iterate will be having the current row’s information.

Is there anything we can achieve this within the fgetcsv loop? I am also open for other alternatives for this problem.

Answer 1

You have to store these rows yourself.

I would do something like this:

$rows = array();

$index = 0;

while(($data = fgetcsv($handle, 5000, ",")) !== FALSE) {
    $rows[] = $data;

    if($index >= 6) {
        $currentIndex = $index - 4;
        $currentRow = $rows[$currentIndex];
        //Do something with $rows[$currentRowIndex +- 3];    
    }
    $index++;
}

If the data is too big to keep it all stored in an array, you could also opt to only store at most 7 rows, and operate on row 4:

$rows = array();

while(($data = fgetcsv($handle, 5000, ",")) !== FALSE) {
    $rows[] = $data;
    if(count($rows) == 7) {
        $currentRow = $rows[4];
        //Do something with $rows[0-6];
        array_shift($rows);    
    }
}