Python not executing write command

Question

Python does not finish the following function (using iPython Notebook and Graphlab)

def print_submission_file(var, filename='submission.txt'):
    with open(filename, 'w') as f:
        f.write('Id,Sales\n')
        for row in var:
            f.write(str(row['Id']) + ',' + str(row['Prediction']) + '\n')

print_submission_file(test, 'submission.txt')

This is the log when the script is stopped (after 5/10 mins)

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-9-f51bf8359fb9> in <module>()
  5             f.write(str(row['Id']) + ',' + str(row['Prediction']) + '\n')
  6 
----> 7 print_submission_file(test, 'submission.txt')

<ipython-input-9-f51bf8359fb9> in print_submission_file(var, filename)
  2     with open(filename, 'w') as f:
  3         f.write('Id,Sales\n')
----> 4         for row in var:
  5             f.write(str(row['Id']) + ',' + str(row['Prediction']) + '\n')
  6 

/Users/MaximeDeBruyn/.graphlab/anaconda/lib/python2.7/site-packages/graphlab/data_structures/sframe.pyc in generator()
   3694         def generator():
   3695             elems_at_a_time = 262144
-> 3696             self.__proxy__.begin_iterator()
   3697             ret = self.__proxy__.iterator_get_next(elems_at_a_time)
   3698             column_names = self.column_names()

graphlab/cython/cy_sframe.pyx in        graphlab.cython.cy_sframe.UnitySFrameProxy.begin_iterator()

graphlab/cython/cy_sframe.pyx in graphlab.cython.cy_sframe.UnitySFrameProxy.begin_iterator()

RuntimeError: Runtime Exception. Canceled by user

So the function writes "Id, Sales" in the submission.txt but never finishes the for loop... Thank you for your help. I really don't know what to do.

Answer 1

Your loop is probably just taking a long time to iterate through the SFrame that way. The error message is because you cancelled the command with Ctrl-C (I'm guessing).

If you want to write a csv with just those two columns, try this (assuming var is an SFrame):

var[['Id','Prediction']].save("submission", format="csv")