TypeError: unhashable 'list'

Question

I am building a program for comparing each promocode(might contain ocr error) in a list to all the promocode in another list(list of correct promocodes)

the expected output is edit distance and the promo code with least edit distance to the one which is getting compared.

my code

import csv
from nltk.metrics import distance

with open("all_correct_promo.csv","rb") as file1:
    reader1 = csv.reader(file1)
    correctPromoList = list(reader1)
    #print correctPromoList

with open("all_extracted_promo.csv","rb") as file2:
    reader2 = csv.reader(file2)
    extractedPromoList = list(reader2)
    #print extractedPromoList

def find_min_edit(str_,list_):
    nearest_correct_promos = []
    distances = {}
    min_dist = 100 # arbitrary large assignment
    for correct_promo in list_:
        dist = distance.edit_distance(extracted,correct_promo,True) # compute Levenshtein distance
        distances[correct_promo] = dist # store each score for real promo codes
        if dist<min_dist:
            min_dist = dist # store min distance
    # extract all real promo codes with minimum Levenshtein distance
    nearest_correct_promos.append(','.join([i[0] for i in distances.items() if i[1]==min_dist])) 
    return ','.join(nearest_correct_promos) # return a comma separated string of nearest real promo codes

incorrectPromo = {}
count = 0
for extracted in extractedPromoList:
    print 'Computing %dth promo code...' % count
    incorrectPromo[extracted] =  find_min_edit(extracted,correctPromoList) # get comma separated str of real promo codes nearest to extracted
    count+=1
print incorrectPromo

Expected output

Computing 0th promo code...
Computing 1th promo code...
Computing 2th promo code...
{'abc': 'abc', 'abd': 'abx,aba,abz,abc', 'acd': 'abx,aba,abz,abc'}

BUT, my code is showing the following errors

Computing 0th promo code...

Traceback (most recent call last):

  File "correctpromo_test4.py", line 31, in <module>

    incorrectPromo[extracted] =  find_min_edit(extracted,correctPromoList) # get 
comma separated str of real promo codes nearest to extracted

 File "correctpromo_test4.py", line 20, in find_min_edit

    distances[correct_promo] = dist # store each score for real promo codes

TypeError: unhashable type: 'list'

Answer 1

You are reading the CSV as a list of lists - the function find_min_edit() is expecting a list of strings as its second argument; what you are passing is a list of lists of strings.

Changing the way you read the csv files with sort this stuff out -

Instead of

with open("all_correct_promo.csv","rb") as file1:
    reader1 = csv.reader(file1)
    correctPromoList = list(reader1)

Just use this

with open("all_correct_promo.csv","rb") as file1:
    reader1 = csv.reader(file1)
    correctPromoList = [''.join(i) for i in reader1]
    print correctPromoList

Do this for both the CSVs, that will sort it out...