How to create a normal distribution in pytorch

Question

I want to create a random normal distribution with a given mean and std.

Answer 1

You can easily use torch.Tensor.normal_() method.

Let's create a matrix Z (a 1d tensor) of dimension 1 × 5, filled with random elements samples from the normal distribution parameterized by mean = 4 and std = 0.5.

torch.empty(5).normal_(mean=4,std=0.5)

Result:

tensor([4.1450, 4.0104, 4.0228, 4.4689, 3.7810])

Answer 2

For a standard normal distribution (i.e. mean=0 and variance=1), you can use torch.randn()

For your case of custom mean and std, you can use torch.distributions.Normal()

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Init signature:
tdist.Normal(loc, scale, validate_args=None)

Docstring:
Creates a normal (also called Gaussian) distribution parameterized by loc and scale.

Args:
loc (float or Tensor): mean of the distribution (often referred to as mu)
scale (float or Tensor): standard deviation of the distribution (often referred to as sigma)

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Here's an example:

In [32]: import torch.distributions as tdist

In [33]: n = tdist.Normal(torch.tensor([4.0]), torch.tensor([0.5]))

In [34]: n.sample((2,))
Out[34]: 
tensor([[ 3.6577],
        [ 4.7001]])