HoVerNet Mode and Branch to independent StrEnum (#5219)

Fixes #5218 

### Description

This PR moves `HoVerNet` Mode and Branch outside of the module and make
them independent `StrEnums`.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [x] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [x] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [x] In-line docstrings updated.

Signed-off-by: Behrooz <3968947+drbeh@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: bhashemian

monai/networks/nets/hovernet.py

@@ -28,7 +28,6 @@
 # =========================================================================
 
 from collections import OrderedDict
-from enum import Enum
 from typing import Callable, Dict, List, Optional, Sequence, Type, Union
 
 import torch
@@ -37,8 +36,8 @@
 from monai.networks.blocks import UpSample
 from monai.networks.layers.factories import Conv, Dropout
 from monai.networks.layers.utils import get_act_layer, get_norm_layer
-from monai.utils import InterpolateMode, UpsampleMode, export
-from monai.utils.enums import StrEnum
+from monai.utils.enums import HoVerNetBranch, HoVerNetMode, InterpolateMode, UpsampleMode
+from monai.utils.module import export, look_up_option
 
 __all__ = ["HoVerNet", "Hovernet", "HoVernet", "HoVerNet"]
 
@@ -380,40 +379,21 @@ class HoVerNet(nn.Module):
       Medical Image Analysis 2019
 
     Args:
+        mode: use original implementation (`HoVerNetMODE.ORIGINAL` or "original") or
+          a faster implementation (`HoVerNetMODE.FAST` or "fast"). Defaults to `HoVerNetMODE.FAST`.
         in_channels: number of the input channel.
         out_classes: number of the nuclear type classes.
         act: activation type and arguments. Defaults to relu.
         norm: feature normalization type and arguments. Defaults to batch norm.
         dropout_prob: dropout rate after each dense layer.
     """
 
-    class Mode(Enum):
-        FAST: int = 0
-        ORIGINAL: int = 1
-
-    class Branch(StrEnum):
-        """
-        Three branches of HoVerNet model, which results in three outputs:
-        `HOVER` is horizontal and vertical regressed gradient map of each nucleus,
-        `NUCLEUS` is the segmentation of all nuclei, and
-        `TYPE` is the type of each nucleus.
-
-        """
-
-        HV = "horizontal_vertical"
-        NP = "nucleus_prediction"
-        NC = "type_prediction"
-
-    def _mode_to_int(self, mode) -> int:
-
-        if mode == self.Mode.FAST:
-            return 0
-        else:
-            return 1
+    Mode = HoVerNetMode
+    Branch = HoVerNetBranch
 
     def __init__(
         self,
-        mode: Mode = Mode.FAST,
+        mode: Union[HoVerNetMode, str] = HoVerNetMode.FAST,
         in_channels: int = 3,
         out_classes: int = 0,
         act: Union[str, tuple] = ("relu", {"inplace": True}),
@@ -423,10 +403,9 @@ def __init__(
 
         super().__init__()
 
-        self.mode: int = self._mode_to_int(mode)
-
-        if mode not in [self.Mode.ORIGINAL, self.Mode.FAST]:
-            raise ValueError("Input size should be 270 x 270 when using Mode.ORIGINAL")
+        if isinstance(mode, str):
+            mode = mode.upper()
+        self.mode = look_up_option(mode, HoVerNetMode)
 
         if out_classes > 128:
             raise ValueError("Number of nuclear types classes exceeds maximum (128)")
@@ -441,7 +420,7 @@ def __init__(
         # number of layers in each pooling block.
         _block_config: Sequence[int] = (3, 4, 6, 3)
 
-        if mode == self.Mode.FAST:
+        if self.mode == HoVerNetMode.FAST:
             _ksize = 3
             _pad = 3
         else:
@@ -510,12 +489,12 @@ def __init__(
 
     def forward(self, x: torch.Tensor) -> Dict[str, torch.Tensor]:
 
-        if self.mode == 1:
+        if self.mode == HoVerNetMode.ORIGINAL.value:
             if x.shape[-1] != 270 or x.shape[-2] != 270:
-                raise ValueError("Input size should be 270 x 270 when using Mode.ORIGINAL")
+                raise ValueError("Input size should be 270 x 270 when using HoVerNetMode.ORIGINAL")
         else:
             if x.shape[-1] != 256 or x.shape[-2] != 256:
-                raise ValueError("Input size should be 256 x 256 when using Mode.FAST")
+                raise ValueError("Input size should be 256 x 256 when using HoVerNetMode.FAST")
 
         x = x / 255.0  # to 0-1 range to match XY
         x = self.input_features(x)
@@ -531,11 +510,11 @@ def forward(self, x: torch.Tensor) -> Dict[str, torch.Tensor]:
         x = self.upsample(x)
 
         output = {
-            HoVerNet.Branch.NP.value: self.nucleus_prediction(x, short_cuts),
-            HoVerNet.Branch.HV.value: self.horizontal_vertical(x, short_cuts),
+            HoVerNetBranch.NP.value: self.nucleus_prediction(x, short_cuts),
+            HoVerNetBranch.HV.value: self.horizontal_vertical(x, short_cuts),
         }
         if self.type_prediction is not None:
-            output[HoVerNet.Branch.NC.value] = self.type_prediction(x, short_cuts)
+            output[HoVerNetBranch.NC.value] = self.type_prediction(x, short_cuts)
 
         return output
 

monai/utils/__init__.py

@@ -29,6 +29,8 @@
     GridPatchSort,
     GridSampleMode,
     GridSamplePadMode,
+    HoVerNetBranch,
+    HoVerNetMode,
     InterpolateMode,
     InverseKeys,
     JITMetadataKeys,

monai/utils/enums.py

@@ -52,6 +52,8 @@
     "ImageStatsKeys",
     "LabelStatsKeys",
     "AlgoEnsembleKeys",
+    "HoVerNetMode",
+    "HoVerNetBranch",
 ]
 
 
@@ -587,3 +589,28 @@ class AlgoEnsembleKeys(StrEnum):
     ID = "identifier"
     ALGO = "infer_algo"
     SCORE = "best_metric"
+
+
+class HoVerNetMode(StrEnum):
+    """
+    Modes for HoVerNet model:
+    `FAST`: a faster implementation (than original)
+    `ORIGINAL`: the original implementation
+    """
+
+    FAST = "FAST"
+    ORIGINAL = "ORIGINAL"
+
+
+class HoVerNetBranch(StrEnum):
+    """
+    Three branches of HoVerNet model, which results in three outputs:
+    `HV` is horizontal and vertical gradient map of each nucleus (regression),
+    `NP` is the pixel prediction of all nuclei (segmentation), and
+    `NC` is the type of each nucleus (classification).
+
+    """
+
+    HV = "horizontal_vertical"
+    NP = "nucleus_prediction"
+    NC = "type_prediction"

tests/test_hovernet.py

@@ -54,6 +54,7 @@
 
 ILL_CASES = [
     [{"out_classes": 6, "mode": 3}],
+    [{"out_classes": 6, "mode": "Wrong"}],
     [{"out_classes": 1000, "mode": HoVerNet.Mode.ORIGINAL}],
     [{"out_classes": 1, "mode": HoVerNet.Mode.ORIGINAL}],
     [{"out_classes": 6, "mode": HoVerNet.Mode.ORIGINAL, "dropout_prob": 100}],