Question

I have a large 2 column csv file (“data.csv”) with a weeks worth of data.
Column one has unix time stamps
Column two has strings:

1329548400,cats
1329548400,dogs
1329550200,fish
1329550200,cats
1329552000,dogs
1329552000,fish
1329584400,cats
1329584400,dogs
1329550200,cats

Via php, I need to convert data.csv into 7 files, Sunday.csv, Monday.csv…Saturday.csv

If I could grab each row, I know I can do something like

$temp = "data.csv";
$fileName = array_unique($temp);
foreach ($fileName as $row) {
    $theDay = date("Y", $row[firstcolumn]);
    if ($theDay == "Sunday") {
        $fileToWriteTo = "Sunday.csv";
        $f = fopen($fileToWriteTo, "a");
        fwrite($fileToWriteTo, $row . "\n");
        fclose($fileToWriteTo);
        }
    if ($theDay == "Monday") {
        $fileToWriteTo = "Monday.csv";
        $f = fopen($fileToWriteTo, "a");
        fwrite($fileToWriteTo, $row . "\n");
        fclose($fileToWriteTo);
        }
    }

Problem is

1) I don’t know how to read each row of data.csv, assuming the syntax above is wrong
2) I admit Im a bit of a php laymen 🙂

…how far off am I? Am I even in the ballpark?

Answer 1

At first, don’t open file at each iteration do it before loop.

$fps = array(); // fps = File Pointers
$days = array( 'Sunday', 'Monday', 'Tuesday', ...);
foreach( $days as $key => $name){
    $fps[ $name] = fopen( 'a', $name . '.csv');
    if( !$fps[ $name]){
        die("Cannot open $name.csv");
    }

    // Although I wouldn't rely on date's `l` format, because
    // it can be localized and script may just stop working
    // and rather use:
    $fps[ $key] = fopen( 'a', $name . '.csv');
    if( $fps[ $key])...
    // Sunday = 7 = 0, Monday = 1...
}

Now, you’ll address fields via date( 'w'), which will give numbers 0 – Sunday, 6 – Saturday:

$day = date( 'w', $timestamp);

About making unique results… You’ll probably need to use function like in_array() and store all processed rows in one array.

About reading and writing CSV files, there are 2 functions: fgetcsv() resp. fputcsv(). So entire loop:

$temp = "data.csv";
$rows = array(); // List of unique itemps
$fp = fopen( $temp, 'r') or die( "Cannot open `$temp` for reading");
// Put here loop which will open all 7 files as mentioned above
// Optionally skip first row (it may contain header)
fgets( $fp);

// Read each row
while( ($array = fgetcsv( $fp, 10000, ',', '"') !== false){
    // Check unique row
    $row = implode( ',', $array);
    if( in_array( $row, $rows)){
         continue; // Skip this iteration
    }
    $rows[] = $row;

    $day = date( 'w', $array[0]);
    fputcsv( $fps[$day], $array);
}

And don’t forget to close all files:

fclose( $fp);
foreach( $fps as $fp){
    fclose( $fp);
}