add collate function + test

ocf_data_sampler/numpy_batch/collate.py

@@ -0,0 +1,79 @@
+from ocf_data_sampler.numpy_batch import NWPBatchKey
+
+import numpy as np
+import logging
+from typing import Union
+
+logger = logging.getLogger(__name__)
+
+
+def stack_np_examples_into_batch(dict_list):
+    """
+    Stacks Numpy examples into a batch
+
+    See also: `unstack_np_batch_into_examples()` for opposite
+
+    Args:
+        dict_list: A list of dict-like Numpy examples to stack
+
+    Returns:
+        The stacked NumpyBatch object
+    """
+    batch = {}
+
+    batch_keys = list(dict_list[0].keys())
+
+    for batch_key in batch_keys:
+        # NWP is nested so treat separately
+        if batch_key == "nwp":
+            nwp_batch: dict[str, NWPBatchKey] = {}
+
+            # Unpack source keys
+            nwp_sources = list(dict_list[0]["nwp"].keys())
+
+            for nwp_source in nwp_sources:
+                # Keys can be different for different NWPs
+                nwp_batch_keys = list(dict_list[0]["nwp"][nwp_source].keys())
+
+                nwp_source_batch = {}
+                for nwp_batch_key in nwp_batch_keys:
+                    nwp_source_batch[nwp_batch_key] = stack_data_list(
+                        [d["nwp"][nwp_source][nwp_batch_key] for d in dict_list],
+                        nwp_batch_key,
+                    )
+
+                nwp_batch[nwp_source] = nwp_source_batch
+
+            batch["nwp"] = nwp_batch
+
+        else:
+            batch[batch_key] = stack_data_list(
+                [d[batch_key] for d in dict_list],
+                batch_key,
+            )
+
+    return batch
+
+
+def _key_is_constant(batch_key):
+    is_constant = batch_key.endswith("t0_idx") or batch_key == NWPBatchKey.channel_names
+    return is_constant
+
+
+def stack_data_list(
+    data_list: list,
+    batch_key: Union[str, NWPBatchKey],
+):
+    """How to combine data entries for each key
+    """
+    if _key_is_constant(batch_key):
+        # These are always the same for all examples.
+        return data_list[0]
+    try:
+        return np.stack(data_list)
+    except Exception as e:
+        logger.debug(f"Could not stack the following shapes together, ({batch_key})")
+        shapes = [example.shape for example in data_list]
+        logger.debug(shapes)
+        logger.error(e)
+        raise e

tests/conftest.py

@@ -7,6 +7,7 @@
 import tempfile
 
 from ocf_data_sampler.config.model import Site
+from ocf_data_sampler.config import load_yaml_configuration, save_yaml_configuration
 
 _top_test_directory = os.path.dirname(os.path.realpath(__file__))
 
@@ -269,3 +270,18 @@ def uk_gsp_zarr_path(ds_uk_gsp):
         ds_uk_gsp.to_zarr(filename)
         yield filename
 
+
+@pytest.fixture()
+def pvnet_config_filename(
+    tmp_path, config_filename, nwp_ukv_zarr_path, uk_gsp_zarr_path, sat_zarr_path
+):
+
+    # adjust config to point to the zarr file
+    config = load_yaml_configuration(config_filename)
+    config.input_data.nwp["ukv"].zarr_path = nwp_ukv_zarr_path
+    config.input_data.satellite.zarr_path = sat_zarr_path
+    config.input_data.gsp.zarr_path = uk_gsp_zarr_path
+
+    filename = f"{tmp_path}/configuration.yaml"
+    save_yaml_configuration(config, filename)
+    return filename

tests/numpy_batch/test_collate.py

@@ -0,0 +1,26 @@
+from ocf_data_sampler.numpy_batch import GSPBatchKey, SatelliteBatchKey
+from ocf_data_sampler.numpy_batch.collate import stack_np_examples_into_batch
+from ocf_data_sampler.torch_datasets import PVNetUKRegionalDataset
+
+
+def test_pvnet(pvnet_config_filename):
+
+    # Create dataset object
+    dataset = PVNetUKRegionalDataset(pvnet_config_filename)
+
+    assert len(dataset.locations) == 317
+    assert len(dataset.valid_t0_times) == 39
+    assert len(dataset) == 317 * 39
+
+    # Generate 2 samples
+    sample1 = dataset[0]
+    sample2 = dataset[1]
+
+    batch = stack_np_examples_into_batch([sample1, sample2])
+
+    assert isinstance(batch, dict)
+    assert "nwp" in batch
+    assert isinstance(batch["nwp"], dict)
+    assert "ukv" in batch["nwp"]
+    assert GSPBatchKey.gsp in batch
+    assert SatelliteBatchKey.satellite_actual in batch

tests/torch_datasets/test_pvnet_uk_regional.py

@@ -6,19 +6,6 @@
 from ocf_data_sampler.numpy_batch import NWPBatchKey, GSPBatchKey, SatelliteBatchKey
 
 
-@pytest.fixture()
-def pvnet_config_filename(tmp_path, config_filename, nwp_ukv_zarr_path, uk_gsp_zarr_path, sat_zarr_path):
-
-    # adjust config to point to the zarr file
-    config = load_yaml_configuration(config_filename)
-    config.input_data.nwp['ukv'].zarr_path = nwp_ukv_zarr_path
-    config.input_data.satellite.zarr_path = sat_zarr_path
-    config.input_data.gsp.zarr_path = uk_gsp_zarr_path
-
-    filename = f"{tmp_path}/configuration.yaml"
-    save_yaml_configuration(config, filename)
-    return filename
-
 
 def test_pvnet(pvnet_config_filename):