Excel to JSON parser with http download I've been working on a project (link) to download a spreadsheet of known ransomware and properties and turn it into json so I can better consume the information within early detection projects.

I'm new to python - what can I be doing better? The destination json I'm converting can be found here.

update_json.py (entry point)

from excel_to_json import excel_to_json
from download_file import download_file

SOURCESHEET = 'https://docs.google.com/spreadsheets/d/1TWS238xacAto-fLKh1n5uTsdijWdCEsGIM0Y0Hvmc5g/pub?output=xlsx'
OUTPUTSHEET = '../RansomwareOverview.xlsx'
JSONFILE = '../ransomware_overview.json'

def write_json_file(json_data, filename):
    output = open(filename, 'w')
    output.writelines(json_data)

def generate_json(source_file, download_destination, json_file):
    download_file(source_file, download_destination)
    write_json_file(excel_to_json(download_destination), json_file)

generate_json(SOURCESHEET, OUTPUTSHEET, JSONFILE)


download_file.py

import urllib.request

def download_file(source, destination):
    try:
        urllib.request.urlretrieve(source, destination)
    except IOError:
        print('An error occured trying to write an updated spreadsheet. Do you already have it open?')
    except urllib.error.URLError:
        print('An error occured trying to download the file. Please check the source and try again.')


excel_to_json.py

import simplejson as json
import xlrd
from collections import OrderedDict

def excel_to_json(filename):
    wb = xlrd.open_workbook(filename)
    sh = wb.sheet_by_index(0)
    mw = wb.sheet_by_index(2)

    # List to hold dictionaries
    c_list = []

    # Iterate through each row in worksheet and fetch values into dict
    for rownum in range(1, sh.nrows):
        wares = OrderedDict()
        row_values = sh.row_values(rownum)

        if row_values[6]=="":
            name = row_values[0]
            gre=[name]
        elif "," in row_values[6]:
            e=row_values[6].split(",")
            ge = [row_values[0]]
            gre=e+ge
        else:
            gre=[row_values[0],row_values[6]]

        wares['name'] = gre
        wares['extensions'] = row_values[1]
        wares['extensionPattern'] = row_values[2]
        wares['ransomNoteFilenames'] = row_values[3]
        wares['comment'] = row_values[4]
        wares['encryptionAlgorithm'] = row_values[5]
        wares['decryptor'] = row_values[7]
        if row_values[8]=="":
            wares['resources'] = [row_values[9]]
        elif row_values[9]=="":
            wares['resources']=[row_values[8]]
        else:
            wares['resources'] = [row_values[8], row_values[9]]
        wares['screenshots'] = row_values[10]

        for r in range(1, mw.nrows):
            rowe = mw.row_values(r)

            if row_values[0] == rowe[0]:
                wares['microsoftDetectionName']=rowe[1]
                wares['microsoftInfo'] = rowe[2]
                wares['sandbox'] = rowe[3]
                wares['iocs'] = rowe[4]
                wares['snort'] = rowe[5]

        c_list.append(wares)

    # Serialize the list of dicts to JSON
    return json.dumps(c_list, indent=4)
Performance tips:


ujson can bring more speed
since both simplejson and xlrd are pure-python, you may get performance improvements "for free" by switching to PyPy
you may (or not) see speed and memory usage improvements if switching to openpyxl and especially in the "read-only" mode
in the excel_to_json function, you are accessing the same values from row_values by index multiple times. Defining intermediate variables (e.g. defining name = row_values[6] and using name variable later on) and avoiding accessing an element by index more than once might have a positive impact 
I'm not sure I completely understand the inner for r in range(1, mw.nrows) loop. Can you break once you get the if row_values[0] == rowe[0] evaluated to True?
are you sure you need the OrderedDict and cannot get away with a regular dict? (there is a serious overhead for CPythons prior to 3.6)
instead of .dumps() and a separate function to dump a JSON string to a file - use .dump() method to dump to a file directly - make sure to use with context manager when opening a file


Code Style notes:


follow PEP8 guidelines in terms of whitespace usage in expressions and statements
properly organize imports
if row_values[6]=="": can be simplified to if not row_values[6]: (similar for some other if conditions later on)
the generate_json() call should be put into the if __name__ == '__main__': to avoid it being executed on import
the excel_to_json() function is not quite easy to grasp - see if you can add a helpful docstring and/or comments to improve on clarity and readability 


Other notes:


improve variable naming. Variables like sh, mw, rowe are very close to being meaningless. I would also replace wb with a more explicit workbook 
have you considered using pandas.read_excel() to read the contents into the dataframe and then dumping it via .to_json() (after applying the desired transformations)?