Getting params by key gives an error without removing prefix

Gluon
1

Hi,

I am a bit confused about accessing the weights in a network.

>>> net = model_zoo.get_model("VGG16", pretrained=True)
>>> all_params = net.collect_params()

all params is of type ParameterDict.

When I iterate over its keys and values:

>>> for k, v in net.collect_params().items():
>>>     print(f"{k:>30} - {v.name}")
     
             vgg0_conv0_weight - vgg0_conv0_weight
               vgg0_conv0_bias - vgg0_conv0_bias
             vgg0_conv1_weight - vgg0_conv1_weight
               vgg0_conv1_bias - vgg0_conv1_bias
             vgg0_conv2_weight - vgg0_conv2_weight

                             ... etc

I see the keys of the ParameterDict and the name of the Parameter.

However, when trying to access the value by its key, like:

>>> net.collect_params().get("vgg0_conv0_weight").data()

I get the error:
RuntimeError: Parameter 'vgg0_vgg0_conv0_weight' has not been initialized.

When I remove the prefix VGG0_, it works:

>>> net.collect_params().get("conv0_weight").data()

[[[[-0.03772613 -0.06753712  0.09550434]
   [-0.12510349 -0.1030491   0.03194679]
   [ 0.04482884  0.02893391  0.07695705]]

... etc

<NDArray 64x3x3x3 @cpu(0)>

In other words, when requesting the keys by:

>>> net.collect_params().keys()

you cannot use this result to query a value by key, without manually removing a prefix. Am I doing something wrong? Is this intended behaviour or a bug?

Best,
Blake