How is that pandas is faster than pure C in the groupby operation? Question: I have an nparray of x,y pairs with shape (n,2), and knowing for certain that for each x there are multiple values of y , I wanted to calculate the average value of y for each unique x. It occurred to …
I need help to speed up of a Python for-loop with huge amount of calculations Question: I am working on a pice of Python software that requires to run a huge amount of calculations. I am talking about up to hundred of millions of calculations or more (n in below code can be 100000 or …
Dataframe of start and end dates into sum of days in an array of periods Question: I have a pandas data frame of start and end dates for contracts. I want to work out the number of in force contract days for all periods (e.g. months) covered by the contracts. Example input: start_date end_date 0 …
Why is 0/1 faster than False/True for this sieve in PyPy? Question: Similar to why use True is slower than use 1 in Python3 but I’m using pypy3 and not using the sum function. def sieve_num(n): nums = [0] * n for i in range(2, n): if i * i >= n: break if nums[i] …
What is the fastest way to sum two strings made up of only numbers but without converting each to an int beforehand? Question: If I am given two strings made up of only numbers 0-9, what is the fastest way to sum the two? Doing something like str(int(num1) + int(num2)) is not allowed and fails. …
Finding the longest interval with a decrease in value faster than quadratic time Question: I have a list of values for some metric, e.g.: # 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 [50, 52, 58, 54, 57, 51, 55, 60, 62, 65, 68, 72, 62, …
Iterating over dictionary or its items Question: What’s a better practice and what’s faster: iterating over dictionary (practically by its keys): for key in dictionary: … or iterating over its items: for key, value in dictionary.items(): …? Using dict.items() seems to be a more clean way to iterate over a dictionary, but isn’t it slower …
Index matrix but return a list of lists Pytorch Question: I have a 2-dimensional tensor and I would like to index it so that the result is a list of lists. For example: R = torch.tensor([[1,2,3], [4,5,6]]) mask = torch.tensor([[1,0,0],[1,1,1]], dtype=torch.bool) output = R[mask] This makes output as tensor([1, 4, 5, 6]). However, I would …
Random dont chose 8 character words Question: I used random module in my ptoject. Im not a programmer, but i need to do a script which will create a randomized database from another database. In my case, I need the script to select random words lined up in a column from the "wordlist.txt" file, and …
Does PriorityQueue call sorted every time get is called? Question: The docs for queue.PriorityQueue say: The lowest valued entries are retrieved first (the lowest valued entry is the one returned by sorted(list(entries))[0]). Does that mean that every time I use the get method of a PriorityQueue that the elements are re-sorted? That would seem inefficient. …
