Question

A simplification of my dictionary:

my_dict = {
    'DOC': [
        [('k', 'v'), ('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3'), ('k4', 'v4')],
        [('k5', 'v5'), ('k', 'v'), ('k1', 'v1'), ('k6', 'v6')]
    ],
    'DIC': [
        [('k7', 'v7'), ('k3', 'v3'), ('k8', 'v8')],
        [('k5', 'v5'), ('k3', 'v3'), ('k1', 'v1'), ('k2', 'v2')],
        [('k4', 'v4'), ('k9', 'v9')]
    ],
    'INFRA': [
        [('k5', 'v5'), ('k3', 'v3'), ('k1', 'v1'), ('k2', 'v2')],
        [('k', 'v'), ('k1', 'v1'), ('k2', 'v2'), ('k3', 'v3'), ('k4', 'v4')]
    ]
}

Overwriting my dictionary values:

for k, v in my_dict.items():
     my_dict[k] = map(lambda x: dict(x), my_dict[k])

Returning…

my_dict 
{'DIC': [{'k3': 'v3', 'k7': 'v7', 'k8': 'v8'},
         {'k1': 'v1', 'k2': 'v2', 'k3': 'v3', 'k5': 'v5'},
         {'k4': 'v4', 'k9': 'v9'}],
 'DOC': [{'k': 'v', 'k1': 'v1', 'k2': 'v2', 'k3': 'v3', 'k4': 'v4'},
         {'k': 'v', 'k1': 'v1', 'k5': 'v5', 'k6': 'v6'}],
 'INFRA': [{'k1': 'v1', 'k2': 'v2', 'k3': 'v3', 'k5': 'v5'},
           {'k': 'v', 'k1': 'v1', 'k2': 'v2', 'k3': 'v3', 'k4': 'v4'}]}

When I ran my real code following the same logic I got the error:

ValueError: dictionary update sequence element #0 has length 6; 2 is required

I’ve tried to create another dictionary to receive the map() but the same error occurred. Someone could help me?

Answer 1

The dict constructor expects a sequence of 2 item subsequences (lists or tuples). At least one of subsequences contains more then two items.

Perhaps you have missing comma (see last item):

>>> dict([('1', 'red'),('2', 'blue'),('3' 'purple')]) # missing comma in last item
Traceback (most recent call last):
  File "<pyshell#166>", line 1, in <module>
    dict([('1', 'red'),('2', 'blue'),('3' 'purple')]) 
ValueError: dictionary update sequence element #2 has length 7; 2 is required

Or maybe a single item instead of a tuple (again, see last item)

>>> dict([('1', 'red'),('2', 'blue'),('purple')]) # last "tuple" has one item
Traceback (most recent call last):
  File "<pyshell#167>", line 1, in <module>
    dict([('1', 'red'),('2', 'blue'),('purple')])
ValueError: dictionary update sequence element #2 has length 6; 2 is required