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How pickle helps in reading huge csv files?

+1 vote
737 views

I've a huge csv file and I want to read stuff from it again and again. Is it useful to pickle it and keep and then unpickle it whenever I need to use that data? Is it faster that accessing that file simply by opening it again and again? Please explain?

posted Oct 16, 2013 by Sanketi Garg

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Keep it in memory

1 Answer

+1 vote

What's your definition of huge? Maybe it would be effective to pickle and unpickle but until you try it, perhaps with a relatively small data sample, how can you know? Why can't you leave the file open and keep iterating over the contents?

answer Oct 16, 2013 by Satish Mishra
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+2 votes

Is there a better way to do that:

def Read_CSV_File(filename):
 file = open(filename, "r")
 reader = csv.DictReader(file)
 line = 1
 for row in reader:
 if line < 6:
 reader.next()
 line++
# process the CSV
0 votes

I am trying to export certain data from my PHP form to CSV. I can echo out to screen during testing and I can also export to CSV the static test data (stored in the $contents array) you see below. But I am stuck trying to export the certain fields that I only need to export.
This is my code

// How do I get this info into the CSV?
/*foreach ( $entries as $entry ) :  
    echo $entry['2'];
    echo $entry['3'];
    echo $entry['6'];
endforeach;*/

$csv_headers = [
    'Organisation Name',
    'Registered Charity Number',
    'Address',
    'Phone',
];

$contents = [
  [2014, 6, '1st half', 'roland@fsjinvestor.com', 0, 0],
  [2014, 6, '1st half', 'steve@neocodesoftware.com', 0, 0],
  [2014, 6, '1st half', 'susanne@casamanager.com', 0, 0],
  [2014, 6, '1st half', 'tim', 0, 0]
];

fputcsv($output_handle, $csv_headers);

foreach ( $contents as $content) :
    fputcsv($output_handle, $content);
endforeach;
...