Stupid Question!

Hi there,
Sorry for the stupid and elementary question!
I am totally new to Python and PyTorch.

My question is that I want to multiply a [128,10,512] tensor by a tensor with the length of 10 such that the final output to be a [128*512] tensor. I know how to do that using for loops. However, I am wondering whether there is a direct PyTorch command in this regard.
Thank you in advance for your kind help :slight_smile:

How are you reducing along that dimension? sum?

Thank you for your reply.
Yes, It is Sum

First thing that comes to mind:

# length 10 vector
ten = torch.ones((10))
# 128x10x512 tensor
big = torch.ones((128,10,512))

result = (big*ten.view(1,-1,1)).sum(1).flatten()

We reshape the tensor to be 1x10x1 to align with the other one. Then we sum across that dimension and flatten.

Makes sense?

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Thank you!
That’s great.
What about if “big” is a tensor shaped [batchsize, num_windows, CNN_features], “ten” is a tensor shaped [batchsize, num_windows], and using “ten” we want to map “big” to the “result” tensor with the shape of [batchsize, CNN_features]? i.e.
big = [128,10,512]
ten = [128,10]
result = [128,512]

sum again? I think it’s the same idea.

ten = torch.ones((128,10))
big = torch.ones((128,10,512))

result = (big*ten.view(128,10,1)).sum(1)
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Thank you again!
I learned a lot!

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No question is stupid. I know its overrepeated but No Question Is Stupid!

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btw, use the </> button to add code or three backticks ``` to start and finish the thing. It just makes everything easier and clean formatting. Easier for other people to understand everything.

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