import os
import sys
import argparse
try:
import cStringIO as StringIO
except:
import StringIO
import struct
import json
import csv
def import_data(import_file):
‘‘‘
Imports data from import_file.
Expects to find fixed width row
Sample row: 161322597 0386544351896 0042
‘‘‘
mask = ‘9s14s5s‘
data = []
with open(import_file, ‘r‘) as f:
for line in f:
# unpack line to tuple
fields = struct.Struct(mask).unpack_from(line)
# strip any whitespace for each field
# pack everything in a list and add to full dataset
data.append(list([f.strip() for f in fields]))
return data
def write_data(data, export_format):
‘‘‘
Dispatches call to a specific transformer
and returns data set.
Exception is xlsx where we have to save data in a file.
‘‘‘
if export_format == ‘csv‘:
return write_csv(data)
elif export_format == ‘json‘:
return write_json(data)
elif export_format == ‘xlsx‘:
return write_xlsx(data)
else:
raise Exception("Illegal format defined")
def write_csv(data):
‘‘‘
Transforms data into csv.
Returns csv as string.
‘‘‘
# Using this to simulate file IO,
# as csv can only write to files.
f = StringIO.StringIO()
writer = csv.writer(f)
for row in data:
writer.writerow(row)
# Get the content of the file-like object
return f.getvalue()
def write_json(data):
‘‘‘
Transforms data into json.
Very straightforward.
‘‘‘
j = json.dumps(data)
return j
def write_xlsx(data):
‘‘‘
Writes data into xlsx file.
‘‘‘
from xlwt import Workbook
book = Workbook()
sheet1 = book.add_sheet("Sheet 1")
row = 0
for line in data:
col = 0
for datum in line:
print datum
sheet1.write(row, col, datum)
col += 1
row += 1
# We have hard limit here of 65535 rows
# that we are able to save in spreadsheet.
if row > 65535:
print >> sys.stderr, "Hit limit of # of rows in one sheet (65535)."
break
# XLS is special case where we have to
# save the file and just return 0
f = StringIO.StringIO()
book.save(f)
return f.getvalue()
if __name__ == ‘__main__‘:
# parse input arguments
parser = argparse.ArgumentParser()
parser.add_argument("import_file", help="Path to a fixed-width data file.")
parser.add_argument("export_format", help="Export format: json, csv, xlsx.")
args = parser.parse_args()
if args.import_file is None:
print >> sys.stderr, "You myst specify path to import from."
sys.exit(1)
if args.export_format not in (‘csv‘,‘json‘,‘xlsx‘):
print >> sys.stderr, "You must provide valid export file format."
sys.exit(1)
# verify given path is accesible file
if not os.path.isfile(args.import_file):
print >> sys.stderr, "Given path is not a file: %s" % args.import_file
sys.exit(1)
# read from formated fixed-width file
data = import_data(args.import_file)
# export data to specified format
# to make this Unix-lixe pipe-able
# we just print to stdout
print write_data(data, args.export_format)
原文地址：https://www.cnblogs.com/cmnz/p/8329494.html