All Questions
1,394 questions
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70
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Numpy ints convert into python ints within numpy array
I'm writing code to group points around each point in a curve into concentric regions. Then I find the geometric median of each region as way of determining its "shape".
The point indices ...
3
votes
1
answer
103
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How to extract sub arrays from a larger array with two start and two stop 1-D arrays in Python?
I am looking for a way to vectorize the following code,
# Let cube have shape (N, M, M)
sub_arrays = np.empty(len(cube), 3, 3)
row_start = ... # Shape (N,) and are integers in range [0, M-2]
row_end ...
- 33
0
votes
2
answers
84
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Demystify numpy indexing/slicing
could you please help demystify the following numpy indexing/slicing behaviours? Thanks!
arr = np.arange(60).reshape(3,4,5)
print(arr[2, :, 4]) #1
print(arr[[2], :, 4]) #2
print(arr[2, :, [4]])...
- 99
1
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1
answer
78
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Taking values from numpy array using array of indices
I am trying to find a simple numpy command to take the values of an 3D matrix according to an index array for the second coordinate. This can be done as:
import numpy as np
entry = np.array([[1, 2],[3,...
1
vote
2
answers
80
views
Converting an array of floats into RGBA values in an efficient way
I am trying to create a system to take an array of floats which range from 0.0 to 1.0 and convert them into RGBA values based on a lookup table. The output should be an array that is one dimension ...
- 51
0
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1
answer
73
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Dynamic input to populate Numpy array without for loop for Monte Carlo
I've got some elegant code from other contributors for a Monte Carlo (random walk) using numpy. However, currently the 'vol,' aka standard deviation, is a supplied constant. Ideally, it should vary ...
- 13
0
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3
answers
84
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Indexing overlapping areas of a numpy array
I have a 2D array of zeros (called labels) and a list of its coordinates (called centers). For each of the centers I would like to put a progressive number in a 5x5 cluster around it inside the label ...
- 357
0
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2
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53
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How to index an ndarray of unknown dimensions
I have a python code that uses a numpy array to store multi-dimensional data. The dimensionality of the array is determined at runtime so I cannot know in advance the exact number of dimensions, which ...
- 117
2
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4
answers
138
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Why the result is different? Numpy Slicing and indexing
Basically I want to obtain a part of the variable "cubote". I tried two methods that should work in the same way, but it didn't.
My code:
import numpy as np
# Create a 3x3x3 cube
...
0
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1
answer
48
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Numpy/PyTorch indexing, assigning values over repeats
I am trying to combine assignment and advanced indexing. I have an array of size (batch, x, y, width) and I am trying to assign it to an array of (batch, width) such that the values are repeated over ...
- 77
2
votes
1
answer
55
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Numpy memory error when masking along only certain axis, despite having sufficient RAM
I have a large array and I want to mask out certain values (set them to nodata). But I'm experiencing an out-of-memory error despite having sufficient RAM.
I have shown below an example that ...
- 33
0
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0
answers
23
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python (Apply inflation table to sales table) [duplicate]
I have the below tables:
Sales Table:
enter image description here
Inflation Table:
enter image description here
I want python to update table one values by multiply each value in table one with ...
2
votes
3
answers
282
views
Numpy index argsorted with integer array while retaining sorting order
I have an array x and the result of argsorting it i. I need to sort x (and y, irrelevant here) according to i hundreds of times. It is therefore not doable to sort the data twice, everything needs to ...
- 53
0
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0
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215
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How to save a numpy array in .fvecs
I'm using faiss to create an index out of vector embeddings, which can then be used for performing similarity search. Since my dataset runs into billions, I'm looking for extremely fast (near-optimal) ...
- 162
0
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1
answer
55
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Array coordinate treated as sequence
I am inputting a numpy array, which was generated from an image into a function. That function makes an autostereogram by horizontally repeating the image and shifting certain pixels.
This is done ...
- 171