Questions tagged [numpy-random]

The `random` package within `numpy` deals with generating numbers or symbols according to well-known probability functions.

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How could these alternate numpy `uniform` vs `random` constructions possibly differ?

I had some code that random-initialized some numpy arrays with: rng = np.random.default_rng(seed=seed) new_vectors = rng.uniform(-1.0, 1.0, target_shape).astype(np.float32) # [-1.0, 1.0) new_vectors /= vector_size And all was working well, all…
gojomo
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Numpy - generate random array with restrictions on individual values in array - Portfolio Optimisation

I'm developing a portfolio optimisation code with constraints using monte-carlo simulation. However, I have run into a problem. My problem is as follows: I have a list of instruments ["Multi", "Equity 1", "Equity 2", "Equity 3", "FI", "Cash"] And I…
Dazz W
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Why does numpy.random.Generator.choice provides different results (seeded) with given uniform distribution compared to default uniform distribution?

Simple test code: pop = numpy.arange(20) rng = numpy.random.default_rng(1) rng.choice(pop,p=numpy.repeat(1/len(pop),len(pop))) # yields 10 rng = numpy.random.default_rng(1) rng.choice(pop) # yields 9 The numpy documentation says: The probabilities…
Andrei
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randomly choose N elements from each row of 2d array in python

I have a 2d array, say, a = [ [1, 2, 3, 4], [5, 6,7, 8], [9, 10, 11, 12], ...[21, 22, 23, 24] ], and I would like to pick N elements from each row randomly, based on a probability distribution p which can be different for each row. So basically,…
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Additive poisson noise to an image

I have written a function to add poisson noise to an image using numpy with np.random.poisson(..). The image is already in numpy array form, using grayscale (0-255). I am wandering if it makes more physical sense to provide the numpy function with…
pierresegonne
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Split a list into n randomly sized chunks

I am trying to split a list into n sublists where the size of each sublist is random (with at least one entry; assume P>I). I used numpy.split function which works fine but does not satisfy my randomness condition. You may ask which distribution the…
tcokyasar
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How to use RandomState with Sklearn RandomizedSearchCV on multiple cores

I am puzzled about the right way to use np.random.RandomState with sklearn.model_selection.RandomizedSearchCV when running on multiple cores. I use RandomState to generate pseudo-random numbers so that my results are reproducible. I give…
hsafer
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Getting closest to endpoints of (1,0) using np.random.uniform

-Random numbers can be drawn on the interval (0, 1], i.e., including 1 using: import numpy as np r = np.random.uniform(low=0.0, high=1.0, size=10) I, however, want to generate numbers on the interval (0, 1), i.e., NOT including 1 and 0. Something…
edager
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Python - Are calls to functions of numpy.random thread safe?

According to this answer, it isn't. But this has not been consistend with what I've observed so far. Consider the following script: import numpy as np from multiprocessing.dummy import Pool from queue import…
spurra
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Fastest way to add noise to a numpy array

I have a numpy.ndarray that represents an image and I would like to add random noise to it. I've done some tests and so far the fastest solution I have is to do: def RandomNoise(x): x += np.random.random(x.shape) But when I have big…
FiReTiTi
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Generating random numbers around a set of coordinates without for loop

I have a set of coordinate means (3D) and a set of standard deviations (3D) accompying them like this: means = [[x1, y1, z1], [x2, y2, z2], ... [xn, yn, zn]] stds = [[sx1, sy1, sz1], [sx2, sy2, sz2], ... …
TheCat
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byte array numpy Python 2 vs Python 3

I need to generate tuples of this form : (string, string) or (string, int). I have the following code which seems to work fine in Python 2 but not returning the desired result in Python 3 (tested on Python 3.5) : import string import numpy as…
aviel
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How to randomize all the items in a matrix in python

I'm trying to create a function that accepts a matrix and assigns random variables to each item of said matrix using python. It seems rather simple but I can't seem to get it to work. The two closest tries Ive done were: def MatrixRandomize(v): …
Debo Akeredolu
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Uniformity test on a large set using scipy.stats.kstest

I'm playing around with some hardware entropy creation. I'm using electronic sensors to sample the environment, using A2D with between 12-16 bits of resolution. I'm hypothesizing that the lower-order bits from these readings contain enough noise and…
cbp2
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Numpy's Multivariate Normal example is not clear

I am not sure if this question fits to numpy users or mathematicians. I don't understand how the numpy.random.multivariate_normal's example works. In the bottom of the documentation, it generates a few random values given a mean and covariance…