Add plot method to Levir, and change directory path (microsoft#335)

* add plotting method

* implement test

* axis off

* prediction flag

* requested changes

* indexing fix

tests/datasets/test_levircd.py

@@ -6,6 +6,7 @@
 from pathlib import Path
 from typing import Generator
 
+import matplotlib.pyplot as plt
 import pytest
 import torch
 import torch.nn as nn
@@ -31,7 +32,7 @@ def dataset(
         monkeypatch.setattr(  # type: ignore[attr-defined]
             torchgeo.datasets.utils, "download_url", download_url
         )
-        md5 = "b61c300e9fd7146eb2c8e2512c0e9d39"
+        md5 = "1adf156f628aa32fb2e8fe6cada16c04"
         monkeypatch.setattr(LEVIRCDPlus, "md5", md5)  # type: ignore[attr-defined]
         url = os.path.join("tests", "data", "levircd", "LEVIR-CD+.zip")
         monkeypatch.setattr(LEVIRCDPlus, "url", url)  # type: ignore[attr-defined]
@@ -60,3 +61,12 @@ def test_invalid_split(self) -> None:
     def test_not_downloaded(self, tmp_path: Path) -> None:
         with pytest.raises(RuntimeError, match="Dataset not found or corrupted."):
             LEVIRCDPlus(str(tmp_path))
+
+    def test_plot(self, dataset: LEVIRCDPlus) -> None:
+        dataset.plot(dataset[0], suptitle="Test")
+        plt.close()
+
+        sample = dataset[0]
+        sample["prediction"] = sample["mask"].clone()
+        dataset.plot(sample, suptitle="Prediction")
+        plt.close()

torchgeo/datasets/levircd.py

@@ -7,6 +7,7 @@
 import os
 from typing import Callable, Dict, List, Optional
 
+import matplotlib.pyplot as plt
 import numpy as np
 import torch
 from PIL import Image
@@ -47,6 +48,7 @@ class LEVIRCDPlus(VisionDataset):
     url = "https://drive.google.com/file/d/1JamSsxiytXdzAIk6VDVWfc-OsX-81U81"
     md5 = "1adf156f628aa32fb2e8fe6cada16c04"
     filename = "LEVIR-CD+.zip"
+    directory = "LEVIR-CD+"
     splits = ["train", "test"]
 
     def __init__(
@@ -88,7 +90,7 @@ def __init__(
                 + "You can use download=True to download it"
             )
 
-        self.files = self._load_files(self.root, self.split)
+        self.files = self._load_files(self.root, self.directory, self.split)
 
     def __getitem__(self, index: int) -> Dict[str, Tensor]:
         """Return an index within the dataset.
@@ -120,23 +122,26 @@ def __len__(self) -> int:
         """
         return len(self.files)
 
-    def _load_files(self, root: str, split: str) -> List[Dict[str, str]]:
+    def _load_files(
+        self, root: str, directory: str, split: str
+    ) -> List[Dict[str, str]]:
         """Return the paths of the files in the dataset.
 
         Args:
             root: root dir of dataset
+            directory: sub directory LEVIR-CD+
             split: subset of dataset, one of [train, test]
 
         Returns:
             list of dicts containing paths for each pair of image1, image2, mask
         """
         files = []
-        images = glob.glob(os.path.join(root, split, "A", "*.png"))
+        images = glob.glob(os.path.join(root, directory, split, "A", "*.png"))
         images = sorted([os.path.basename(image) for image in images])
         for image in images:
-            image1 = os.path.join(root, split, "A", image)
-            image2 = os.path.join(root, split, "B", image)
-            mask = os.path.join(root, split, "label", image)
+            image1 = os.path.join(root, directory, split, "A", image)
+            image2 = os.path.join(root, directory, split, "B", image)
+            mask = os.path.join(root, directory, split, "label", image)
             files.append(dict(image1=image1, image2=image2, mask=mask))
         return files
 
@@ -181,7 +186,7 @@ def _check_integrity(self) -> bool:
             True if the dataset directories and split files are found, else False
         """
         for filename in self.splits:
-            filepath = os.path.join(self.root, filename)
+            filepath = os.path.join(self.root, self.directory, filename)
             if not os.path.exists(filepath):
                 return False
         return True
@@ -202,3 +207,53 @@ def _download(self) -> None:
             filename=self.filename,
             md5=self.md5 if self.checksum else None,
         )
+
+    def plot(
+        self,
+        sample: Dict[str, Tensor],
+        show_titles: bool = True,
+        suptitle: Optional[str] = None,
+    ) -> plt.Figure:
+        """Plot a sample from the dataset.
+
+        Args:
+            sample: a sample returned by :meth:`__getitem__`
+            show_titles: flag indicating whether to show titles above each panel
+            suptitle: optional suptitle to use for figure
+
+        Returns:
+            a matplotlib Figure with the rendered sample
+
+        .. versionadded:: 0.2
+        """
+        image1, image2, mask = (sample["image"][0], sample["image"][1], sample["mask"])
+        ncols = 3
+
+        if "prediction" in sample:
+            prediction = sample["prediction"]
+            ncols += 1
+
+        fig, axs = plt.subplots(nrows=1, ncols=ncols, figsize=(10, ncols * 5))
+
+        axs[0].imshow(image1.permute(1, 2, 0))
+        axs[0].axis("off")
+        axs[1].imshow(image2.permute(1, 2, 0))
+        axs[1].axis("off")
+        axs[2].imshow(mask)
+        axs[2].axis("off")
+
+        if "prediction" in sample:
+            axs[3].imshow(prediction)
+            axs[3].axis("off")
+            if show_titles:
+                axs[3].set_title("Prediction")
+
+        if show_titles:
+            axs[0].set_title("Image 1")
+            axs[1].set_title("Image 2")
+            axs[2].set_title("Mask")
+
+        if suptitle is not None:
+            plt.suptitle(suptitle)
+
+        return fig