Printing only the first weights of a neural network

Question

I have my model (a VGG16, but it is not important). I want to check only some parameters of my network, for example the first ones. To do this I do list(model.parameters()) and it prints all the parameters. Now, considering that a VGG has this shape:

VGG16(
  (block_1): Sequential(
    (0): Conv2d(1, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    (2): ReLU()
    (3): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1))
    (4): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
    (5): ReLU()
    (6): MaxPool2d(kernel_size=(2, 2), stride=(2, 2), padding=0, dilation=1, ceil_mode=False)
  )
...

If I want only the weights of the convolutions I do this: list(model.block_1[0].parameters()) and it prints this:

[Parameter containing:
 tensor([[[[-0.3215, -0.0771,  0.4429],
           [-0.6455, -0.0827, -0.4266],
           [-0.2029, -0.2288,  0.1696]]],
 
 
         [[[ 0.5323, -0.2418, -0.1031],
           [ 0.5917,  0.2669, -0.5630],
           [ 0.3064, -0.4984, -0.1288]]],
 
 
         [[[ 0.3804,  0.0906, -0.2116],
           [ 0.2659, -0.3325, -0.1873],
           [-0.5044,  0.0900,  0.1386]]],
 

Now, these lists are always enormous. How can I print only the first values, for example, the first matrix?

[[[[-0.3215, -0.0771,  0.4429],
   [-0.6455, -0.0827, -0.4266],
   [-0.2029, -0.2288,  0.1696]]]

Answer 1

You can treat it as a NumPy array when it's processed correctly. In your example, this should work:

from torchvision import models
model = models.vgg16()
first_param = list(model.features[0].parameters())[0].data

The first_param will hold the tensor as:

tensor([[[[-0.3215, -0.0771,  0.4429],
           [-0.6455, -0.0827, -0.4266],
           [-0.2029, -0.2288,  0.1696]]],
 
 
         [[[ 0.5323, -0.2418, -0.1031],
           [ 0.5917,  0.2669, -0.5630],
           [ 0.3064, -0.4984, -0.1288]]],
 
 
         [[[ 0.3804,  0.0906, -0.2116],
           [ 0.2659, -0.3325, -0.1873],
           [-0.5044,  0.0900,  0.1386]]]

Then just continue as NumPy array:

print(first_param[0])

>> tensor([[[[-0.3215, -0.0771,  0.4429],
             [-0.6455, -0.0827, -0.4266],
             [-0.2029, -0.2288,  0.1696]]])