How to get a uniform distribution in a range [r1,r2] in PyTorch?

Question

The question says it all. I want to get a 2-D torch.Tensor with size [a,b] filled with values from a uniform distribution (in range [r1,r2]

Answer 1

See this for all distributions: https://pytorch.org/docs/stable/distributions.html#torch.distributions.uniform.Uniform

This is the way I found works:

# generating uniform variables

import numpy as np

num_samples = 3
Din = 1
lb, ub = -1, 1

xn = np.random.uniform(low=lb, high=ub, size=(num_samples,Din))
print(xn)

import torch

sampler = torch.distributions.Uniform(low=lb, high=ub)
r = sampler.sample((num_samples,Din))

print(r)

r2 = torch.torch.distributions.Uniform(low=lb, high=ub).sample((num_samples,Din))

print(r2)

# process input
f = nn.Sequential(OrderedDict([
    ('f1', nn.Linear(Din,Dout)),
    ('out', nn.SELU())
]))
Y = f(r2)
print(Y)

but I have to admit I don't know what the point of generating sampler is and why not just call it directly as I do in the one liner (last line of code).

Comments:

• sampler are good for it's so you can transform/compose/cache/etc distributions. see https://arxiv.org/abs/1711.10604, and the top of the docs of https://pytorch.org/docs/stable/distributions.html# and https://arxiv.org/abs/1506.05254
• you can feed in tensors to uniform to let it know the high dimensional interval (hypercube) to generate the uniform samples (that's why it receives tensors as input rather than simply numbers)

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Reference:

• How to get a uniform distribution in a range [r1,r2] in PyTorch?
• https://discuss.pytorch.org/t/generating-random-tensors-according-to-the-uniform-distribution-pytorch/53030/8
• https://github.com/pytorch/pytorch/issues/24162