CODEWITHSUNDEEP
pythonlistdictionaryrecursion
AdrianBoeh
AdrianBoeh

Reputation: 176

Python Nested Dictionary to List of Lists

I know this has already been ask many ways, and I tried to read most of them, but still having trouble...

I have the nested dictionary

city = {'centerLatitude': '40',
 'centerLongitude': '-86',
 'listings': {'A Name Here': {'address': 'the address',
                                     'city': 'acity',
                                     'distance': 'AmillionMiles',
                                     'facility_id': '1234',
                                     'latitude': '34',
                                     'longitude': '-86',
                                     'price': 'tooMuch',
                                     'rating': 'supergreat',
                                     'size': "10'xAz'",
                                     'state': 'XY',
                                     'zip': '50505'}}}

I have this recursive python function (taken from another post)

def grab_children(father):
local_list = []
for key, value in father.iteritems():
    local_list.append(key)
    local_list.extend(grab_children(value))
return local_list

Calling the function with

print grab_children(city)

And I get this error... rather than a list

Traceback (most recent call last):
  File "<pyshell#19>", line 1, in <module>
    print grab_children(city)
  File "<pyshell#5>", line 5, in grab_children
    local_list.extend(grab_children(value))
  File "<pyshell#5>", line 3, in grab_children
    for key, value in father.iteritems():
AttributeError: 'str' object has no attribute 'iteritems'

From the error I thought that there was something going on with the value used when the function calls itself again because it looks like it thinks it is a str which yes, has no .iteritems, but running it in pieces and printing type(value) it is always a dictionary (like it should be).

It works with this dictionary, also taken from another post, and I do not understand what is different about this dictionary.

city = {'<Part: 1.1>': {'<Part: 1.1.1>': {'<Part: 1.1.1.1>': {}},
                 '<Part: 1.1.2>': {}},
 '<Part: 1.2>': {'<Part: 1.2.1>': {}, '<Part: 1.2.2>': {}},
 '<Part: 1.3>': {}}

My questions are: Why am I getting this error? How do I over come the error? And if the error is caused by my dictionary being different, how is it different?

Upvotes: 0

Views: 4143

Answers (3)

LetzerWille
LetzerWille

Reputation: 5658

your function should be changed to check if value is a dict, error  
because you recursive function tries to run iteritems() on a value that isstring. 
if isinstance(value,dict): clause need to be added to this recursive function. 
Otherwise function eventually grabs a string..
         change items() to iteritems() if not python 3

    def grab_children(father):
        local_list = []
        for key, value in father.items():
            local_list.append(key)
            if isinstance(value,dict):
                local_list.extend(grab_children(value))
        return local_list

print(grab_children(city))

['centerLatitude', 'centerLongitude', 'listings', 'A Name Here', 'latitude', 'rating', 'zip', 'longitude', 'facility_id', 'size', 'city', 'distance', 'state', 'address', 'price']

Upvotes: 1

Felipe Gerard
Felipe Gerard

Reputation: 1622

You never put a stopping condition. The following retrieves all the keys in all the dictionaries:

def grab_children(father):
    local_list = []
    for key, value in father.iteritems():
        local_list.append(key)
        if type(value) is dict:
            local_list.extend(grab_children(value))
    return local_list

Upvotes: 0

RobertB
RobertB

Reputation: 1929

Notice in the sample that the "leaves" are all "{}". That is an empty dict. In your "city" your leaves are strings. To use this function as written, then instead of: 

city = {'centerLatitude': '40'}

You would have to write:

city = { 'centerLatitude': { '40' : {} } }

etc.

But this question topic says "List of Lists" and that is not what your sample code does. Your sample code returns a single list. So I'm not really sure what you want as output.

Upvotes: 3

Related Questions