empty List after converting csv file to dictionary

Question

I have converted a csv file to a list of dictionaries.

csvfile = './xyz.csv'

jsonArray = []

with open(csvfile, encoding='utf_8_sig') as csvf:
   csvReader = csv.DictReader(csvf)

   for row in csvReader:
      jsonArray.append(row)

When I print the result it looks like this (list of dicts):

[
{
    'Meter-id': 'W000001',
    'January': '7.20',
    'February': '7.2010',
    'March': '7.34',
    'April': '7.4870',
},
{
    'Meter-id': 'W000002',
    'January': '301,069.00',
    'February': '318,592.000',
    'March': '331,158.00',
    'April': '345,322.000',
},
{
    'Meter-id': 'K000001',
    'January': '767,410.80',
    'February': '784,932.700',
    'March': '797,636.90',
    'April': '812,111.000',
},...
]

But when I try to use the Array to group the dictionaries but the array seems empty:

resp = defaultdict(list)

KEY_MAP = {
  'W': 'Warm',
  'K': "Cold"
  }

for key, group in itertools.groupby(jsonArray, key=lambda x: KEY_MAP.get(x["Meter-id"][0])):
for thing in group:
    resp[key].append(thing)

What am I doing wrong here?

Thank you in advance

A

Answer 1

Your code and your sample works well for me (except indentation). Maybe you can try a version without groupby (especially if your json array is not sorted by group)

Update :

How can I fix IndexError: string index out of range

Do not use [0] but a slice like [:1] to not raise an exception and use default argument of dict.get to return a default group:

resp = defaultdict(list)
for x in jsonArray:
    group = KEY_MAP.get(x["Meter-id"][:1], 'Misc')
    resp[group].append(x)

In each method, the output is:

defaultdict(list,
            {'Warm': [{'Meter-id': 'W000001',
               'January': '7.20',
               'February': '7.2010',
               'March': '7.34',
               'April': '7.4870'},
              {'Meter-id': 'W000002',
               'January': '301,069.00',
               'February': '318,592.000',
               'March': '331,158.00',
               'April': '345,322.000'}],
             'Cold': [{'Meter-id': 'K000001',
               'January': '767,410.80',
               'February': '784,932.700',
               'March': '797,636.90',
               'April': '812,111.000'}]})