Hi, I’m trying to make a simple fit of the form w1 * sin (w2*x +w3) but the results are somehow strange. Maybe someone can help. Here’s my code:
# create model
import torch
from torch import nn
from torch.autograd import Variable

class MyModel(nn.Module):
    def __init__(self):
        super(MyModel, self).__init__()
        self.w1 = nn.Parameter(torch.Tensor(np.random.randn(1)))
        self.w2 = nn.Parameter(torch.Tensor(np.random.randn(1)))
        self.w3 = nn.Parameter(torch.Tensor(np.random.randn(1)))
        return
    
    def forward(self, input):
        w1, w2, w3 = self.w1, self.w2, self.w3
        return w1* torch.sin(w2 * input + w3)
import numpy as np
import holoviews as hv
hv.extension('bokeh')

# helper function
def f(w1, w2, w3):
    def f2(x):
        return w1 * np.sin(w2*x + w3)
    return f2


def run_and_plot(w1=1, w2=1, w3=1 ,noise=0.01):
    # make some data
    x_numpy = np.linspace(-5, 5, 1000)
    y_no_noise_numpy = f(w1, w2, w3)(x_numpy)

    # add noise 
    y_numpy = y_no_noise_numpy + noise * np.random.standard_normal(y_no_noise_numpy.size)

    # convert
    x = torch.autograd.Variable(torch.Tensor(x_numpy),
         requires_grad=False)
    y = torch.autograd.Variable(torch.Tensor(y_numpy),
         requires_grad=False)
    
    # initialize model, optimizer, loss_function    
    model = MyModel()
    optimizer = torch.optim.RMSprop(model.parameters(), lr=0.01)
    loss_function = nn.MSELoss()
    
    
    for epoch in range(1000):
        y_pred = model(x) 
        loss = loss_function(y_pred, y)
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()
    curf = hv.Points((x_numpy, y_numpy))
    curf2 = hv.Curve((x_numpy,y_pred.data.numpy()))
    return (curf*curf2).relabel('%.2f   %.2f   %.2f   %.2f' % (w1, w2, w3, noise))

np.random.seed(1)
hv.opts('Curve (color="red")')
(run_and_plot(1, 1 ,1) + run_and_plot(1, 2, 1) + run_and_plot(2, 1, 1) 
 + run_and_plot(1, 1, 2) + run_and_plot(3, 2, 1) + run_and_plot(1, 4, 4)).cols(3)

Here’s the resulting plot. Points to fit blue and resulting curve red.

pytorch.png900×630 73.6 KB

Thanks