Python | Find depth of a dictionary
Prerequisite: Nested dictionary
The task is to find the depth of given dictionary in Python. Let’s discuss all different methods to do this task.
Examples:
Input : {1:'a', 2: {3: {4: {}}}}
Output : 4
Input : {'a':1, 'b': {'c':'geek'}}
Output : 3
Approach #1 : Naive Alpproach
A naive approach in order to find the depth of a dictionary is to count the number of opening curly braces. But, one drawback of this approach is that it would only work if the input is correct.
# Python3 Program to find depth of a dictionary def dict_depth(dic, level = 1): str_dic = str(dic) counter = 0 for i in str_dic: if i == "{": counter += 1 return(counter) # Driver code dic = {1:'Geek', 2: {3: {4: {}}}} print(dict_depth(dic)) |
4
Approach #2: Using recursion
In this method we use recursion with max() function which picks the greatest depth for the current dictionary under scrutiny at each level.
# Python3 Program to find depth of a dictionary def dict_depth(dic, level = 1): if not isinstance(dic, dict) or not dic: return level return max(dict_depth(dic[key], level + 1) for key in dic) # Driver code dic = {1:'a', 2: {3: {4: {}}}} print(dict_depth(dic)) |
4
Another version of the recursive solution is to use map() function by which the values of the inner dictionary is mapped to the called function.
# Python3 Program to find depth of a dictionary def dict_depth(my_dict): if isinstance(my_dict, dict): return 1 + (max(map(dict_depth, my_dict.values())) if my_dict else 0) return 0 # Driver code my_dict = {1:'a', 2: {3: {4: {}}}} print(dict_depth(my_dict)) |
4
Approach #3: Iterative Solution
In this approach, we save the nested key and its initial depth in a variable, say p_dict. Now, start a loop for p_dict, and keep popping values while digging deeper for nested dictionaries.
# Python3 Program to find depth of a dictionary def dict_depth(myDict): Ddepth = 1 obj = [(k, Ddepth + 1) for k in myDict.values() if isinstance(k, dict)] max_depth = 0 while(obj): n, Ddepth = obj.pop() max_depth = max(max_depth, Ddepth) obj = obj + [(k, Ddepth + 1) for k in n.values() if isinstance(k, dict)] return max_depth # Driver code myDict = {1:'a', 2: {3: {4:{}}}} print(dict_depth(myDict)) |
4
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