Python. Pushing values to the dictionary in dictionary

Question

I am getting values from some source using which I need to create a dictionary of dictionary. To solve such a task in PHP I would just write a for loop and:

$arr[ifIndex][$key] = $val

I do not need to bother if a $key value really exists in my associative array - it will be created if it isn't. In Python though you get a key error so I have to check that and add a dictionary if it isn't there:

if ifIndex in data:
     data[ifIndex][entry] = val.prettyPrint()
else:
     data[ifIndex] = { entry: val.prettyPrint() }

To me that looks very ugly and I think there is way of doing that as simple as in a PHP example.

Answer 1

a = collections.defaultdict(dict)
a['b']['c'] = 'd'

returns

defaultdict(<type 'dict'>, {'b': {'c': 'd'}})