from monai.transforms import RandCropByPosNegLabeld
import numpy as np


trans = RandCropByPosNegLabeld(keys=['image', 'mask'],
                               image_key='image',
                               label_key='mask',
                               # The third dimension of spatial_size was set as `-1`,
                               # hoping the cropped patch's third dimension is consistent with the original image.
                               spatial_size=(40, 40, -1),
                               num_samples=4)

# image & mask with the shape of [channel, d1, d2, d3]
# In my case, the d3 dimension is the number of slices.

############################################################
# This bug occurs only when the third dimension of `image_1` is bigger than it of `image_2`.
###########################################################
image_1 = np.random.rand(1, 100, 100, 80).astype(np.float32)
mask_1 = np.random.randint(0, 2, (1, 100, 100, 80), dtype=np.int32)

image_2 = np.random.rand(1, 100, 100, 50).astype(np.float32)
mask_2 = np.random.randint(0, 2, (1, 100, 100, 50), dtype=np.int32)

data_1 = {'image':image_1, 'mask':mask_1}
data_2 = {'image':image_2, 'mask':mask_2}

transformed_1 = trans(data_1)  #`RandCropByPosNegLabeld.spacial_size` (40, 40, -1) has been replaced with (40, 40, 80).

transformed_2 = trans(data_2)  # `RandCropByPosNegLabeld.spacial_size` is (40, 40, 80), but not the expected value (40, 40, 50)
# ValueError: The size of the proposed random crop ROI is larger than the image size.