Question

I have several files, each of which has data like this (filename:data inside separated by newline):

1. Mike: Plane\nCar
2. Paula: Plane\nTrain\nBoat\nCar
3. Bill: Boat\nTrain
4. Scott: Car

How can I create a csv file using python that groups all the different vehicles and then puts a X on the applicable person, like:

Answer 1

Assuming those line numbers aren’t in there (easy enough to fix if they are), and with an input file like following:

Mike: Plane
Car
Paula: Plane
Train
Boat
Car
Bill: Boat
Train
Scott: Car

Solution can be found here : https://gist.github.com/999481

import sys
from collections import defaultdict
import csv

# see http://stackoverflow.com/questions/6180609/group-and-check-mark-using-python
def main():
    # files = ["group.txt"]
    files = sys.argv[1:]
    if len(files) < 1:
        print "usage: ./python_checkmark.py file1 [file2 ... filen]"

    name_map = defaultdict(set)

    for f in files:
        file_handle = open(f, "r")
        process_file(file_handle, name_map)
        file_handle.close()

    print_csv(sys.stdout, name_map) 

def process_file(input_file, name_map):
    cur_name = ""
    for line in input_file:
        if ":" in line:
            cur_name, item = [x.strip() for x in line.split(":")]
        else:
            item = line.strip()
        name_map[cur_name].add(item)


def print_csv(output_file, name_map):
    names = name_map.keys()
    items = set([])
    for item_set in name_map.values():
        items = items.union(item_set)

    writer = csv.writer(output_file, quoting=csv.QUOTE_MINIMAL)
    writer.writerow( [""] + names )
    for item in sorted(items):
        row_contents = map(lambda name:"X" if item in name_map[name] else "", names)
        row = [item] + row_contents
        writer.writerow( row )


if __name__ == '__main__':
    main()

Output:

,Mike,Bill,Scott,Paula 
Boat,,X,,X 
Car,X,,X,X 
Plane,X,,,X 
Train,,X,,X 

Only thing this script doesn’t do is keep the columns in order that the names are in. Could keep a separate list maintaining the order, since maps/dicts are inherently unordered.