Question

I am using DictWriter to output data in a dictionary to a csv file. Why does the CSV file have a blank line in between each data line? It’s not a huge deal, but my dataset is big and doesn’t fit into one csv file because it has too many lines since the “double-spacing” doubles the number of lines in the file.

My code for writing to the dictionary is:

headers=['id', 'year', 'activity', 'lineitem', 'datum']
output = csv.DictWriter(open('file3.csv','w'), delimiter=',', fieldnames=headers)
output.writerow(dict((fn,fn) for fn in headers))
for row in rows:
    output.writerow(row)

Answer 1

By default, the classes in the csv module use Windows-style line terminators (\r\n) rather than Unix-style (\n). Could this be what’s causing the apparent double line breaks?

If so, in python 2 you can override it in the DictWriter constructor:

output = csv.DictWriter(open('file3.csv','w'), delimiter=',', lineterminator='\n', fieldnames=headers)