KeyError Filling Defaultdict Python

Question

I try to populate the default dictionary with csv data and I get a key error

for i in range(0,1):

    #https://docs.python.org/2/library/collections.html#collections.defaultdict
    result = co.defaultdict(list)
    with open(os.path.join(inputdir,tablelist[i])) as f:

        csv_reader = csv.reader(f)
        csv_headings = next(csv_reader)
        read = csv.DictReader(f)

        for line in read:
            for j in range(1,len(csv_headings)):
  error here--->result[line[csv_headings[0]]].append(line[csv_headings[j]])  

for csv data

API,CNTYNM,PRMT,
4700100002,Barbour,2,
4700100003,Barbour,3,
4700100004,Barbour,4,

a key error for the API, which means for me that something with the dictreader is not working properly, can anyone give any advice?

Answer 1

You are missing an argument fieldnamesfor DictReader. If you change your code to go csv_haedingsto DictReader, it will work (hopefully, as expected):

for i in range(0,1):

    #https://docs.python.org/2/library/collections.html#collections.defaultdict
    result = co.defaultdict(list)
    with open(os.path.join(inputdir,tablelist[i])) as f:

        csv_reader = csv.reader(f)
        csv_headings = next(csv_reader)
        read = csv.DictReader(f, fieldnames=csv_headings)

        for line in read:
            for j in range(1,len(csv_headings)):
                result[line[csv_headings[0]]].append(line[csv_headings[j]])