transforms for fastai

transforms.py

from functools import singledispatch

@faiv.TfmPixel
@singledispatch
def crop(x, pct, axis:int) -> torch.Tensor:
    """" crop a 3d image along an axis """
    s = x.shape
    i0, i1 = int(s[axis]*pct[0]), int(s[axis]*pct[1])
    return x[np.newaxis,i0:i1,:,:].contiguous() if axis == 0 else \
           x[np.newaxis,:,i0:i1,:].contiguous() if axis == 1 else \
           x[np.newaxis,:,:,i0:i1].contiguous()
           
tfms = [crop(pct=(0.20,0.80),axis=2)]