"RuntimeError: dictionary changed size during iteration" but it's not changed in the loop Question: I’m solving this LeetCode problem and here’s my code: class Solution: def alienOrder(self, words: List[str]) -> str: adjacent = defaultdict(set) for i in range(1, len(words)): w1, w2 = words[i – 1], words[i] min_len = min(len(w1), len(w2)) if len(w1) > len(w2) and …
Python dict with default value based on key Question: I need a dictionary that is automatically filled with a default value for each accessed key that is missing. I’ve found defaultdict and some other ways to achieve this, but the problem in my case is that I want the default value for each key to …
compare a defaultdict key-value with another defaultdict Question: I have two defaultdict : defaultdict(<type ‘list’>, {‘a’: [‘OS’, ‘sys’, ‘procs’], ‘b’: [‘OS’, ‘sys’]}) defaultdict(<type ‘list’>, {‘a’: [‘OS’, ‘sys’], ‘b’: [‘OS’]}) How do I compare these two to get the count of values missing from each one. For example I should get two values are missing from …
How to initialize defaultdict with keys? Question: I have a dictionary of lists, and it should be initialized with default keys. I guess, the code below is not good (I mean, it works, but I don’t feel that it is written in the pythonic way): d = {‘a’ : [], ‘b’ : [], ‘c’ : …
defaultdict with default value 1? Question: I am new to python, and i read some code snippet from some place. It’s an implementation of counting sort. The code is as below: from collections import defaultdict def sort_colors(A): ht = {} # a hash map ht = defaultdict(lambda:0, ht) # with default value 1 for i …
How to use a DefaultDict with a lambda expression to make the default changeable? Question: DefaultDicts are useful objects to be able to have a dictionary that can create new keys on the fly with a callable function used to define the default value. eg. Using str to make an empty string the default. >>> …
Python Dict Comprehension to Create and Update Dictionary Question: I have a list of dictionaries (data) and want to convert it into dictionary (x) as below. I am using following ‘for loop’ to achieve. data = [{‘Dept’: ‘0123’, ‘Name’: ‘Tom’}, {‘Dept’: ‘0123’, ‘Name’: ‘Cheryl’}, {‘Dept’: ‘0123’, ‘Name’: ‘Raj’}, {‘Dept’: ‘0999’, ‘Name’: ‘Tina’}] x = {} …
Using defaultdict to replace try and/or if statements in python Question: I have recently found and started using default dictionaries to replace several more bulky constructs. I have read in ‘the zen of python’ that one of the key points of python is “There should be one– and preferably only one –obvious way to do …
How to convert defaultdict to dict? Question: How can I convert a defaultdict number_to_letter defaultdict(<class ‘list’>, {‘2’: [‘a’], ‘3’: [‘b’], ‘1’: [‘b’, ‘a’]}) to be a common dict? {‘2’: [‘a’], ‘3’: [‘b’], ‘1’: [‘b’, ‘a’]} Asked By: user2988464 || Source Answers: You can simply call dict: >>> a defaultdict(<type ‘list’>, {‘1’: [‘b’, ‘a’], ‘3’: [‘b’], …
Nested defaultdict of defaultdict Question: Is there a way to make a defaultdict also be the default for the defaultdict? (i.e. infinite-level recursive defaultdict?) I want to be able to do: x = defaultdict(…stuff…) x[0][1][0] {} So, I can do x = defaultdict(defaultdict), but that’s only a second level: x[0] {} x[0][0] KeyError: 0 There …
