Error when plotting Confusion Matrix in Fastai

VNandu · June 16, 2021, 9:36pm

I am getting the following error when plotting the confusion matrix.

Can someone suggest what this error implies?
Thanks very much.

muellerzr · June 17, 2021, 1:26pm

How did you build your dataloaders? Are they raw torch loaders? fastai dataloaders?

VNandu · June 17, 2021, 4:18pm

Hi,

I have used fastai to build my dataloaders.

Thanks.

muellerzr · June 17, 2021, 4:26pm

Can you show the code you used to make it?

VNandu · June 17, 2021, 4:33pm

PLease see the code below:

muellerzr · June 17, 2021, 6:53pm

You’re not using the fastai datablock API here, and that’s the issue. I’m not sure it will work here, but you can try. The confusion matrix and interp were designed for full use of the fastai API (to my knowledge), and so it expects certain things to be there. In this case it’s a classification problem, and fastai stores the number of classes in dls.dataset.c

You need to throw on a c attribute to your dataset (ie the number of classes). So just do dl[0].dataset.c = mynumclasses

VNandu · June 17, 2021, 10:33pm

Thanks so much for the help.