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How does collections.defaultdict work?
I've read the examples in python docs, but still can't figure out what this method means. Can somebody help? Here are two examples from the python docs
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Real-world examples of recursion [closed]
What are real-world problems where a recursive approach is the natural solution besides depth-first search (DFS)?
55 Ans...
How to get first element in a list of tuples?
I have a list like below where the first element is the id and the other is a string:
12 Answers
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Why is a ConcurrentModificationException thrown and how to debug it
I am using a Collection (a HashMap used indirectly by the JPA, it so happens), but apparently randomly the code throws a ConcurrentModificationException . What is causing it and how do I fix this problem? By using some synchronization, perhaps?
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Why use pointers? [closed]
I know this is a really basic question, but I've just started with some basic C++ programming after coding a few projects with high-level languages.
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Why doesn't Dijkstra's algorithm work for negative weight edges?
Can somebody tell me why Dijkstra's algorithm for single source shortest path assumes that the edges must be non-negative.
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Checking if a key exists in a JavaScript object?
How do I check if a particular key exists in a JavaScript object or array?
22 Answers
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(Built-in) way in JavaScript to check if a string is a valid number
I'm hoping there's something in the same conceptual space as the old VB6 IsNumeric() function?
37 Answers
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What does 'predicate' mean in the context of computer science? [duplicate]
Specifically I've seen it used in the context of text filtering. As if "predicate" == "filter criteria".
7 Answers
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Apply a function to every row of a matrix or a data frame
Suppose I have a n by 2 matrix and a function that takes a 2-vector as one of its arguments. I would like to apply the function to each row of the matrix and get a n-vector. How to do this in R?
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