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fix: preserve component sample model band offsets #3108

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fix: preserve component sample model band offsets #3108

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4 changes: 2 additions & 2 deletions python/sedona/spark/raster/sample_model.py
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Original file line number Diff line number Diff line change
Expand Up @@ -80,9 +80,9 @@ def as_numpy(self, data_buffer: DataBuffer) -> np.ndarray:
if self.scanline_stride == self.width and self.pixel_stride == 1:
# Fast path: no gaps between pixels
band_arrs = []
for bank_index in self.bank_indices:
for k, bank_index in enumerate(self.bank_indices):
bank_data = data_buffer.bank_data[bank_index]
offset = self.band_offsets[bank_index]
offset = self.band_offsets[k]

@jiayuasu jiayuasu Jul 16, 2026

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Could we calculate the effective start here (data_buffer.offsets[bank_index] + self.band_offsets[k]) and always slice a width * height window? I may be missing an invariant, but a component model can have a zero band offset with a padded backing bank; then the current branch seems to pass the whole bank to reshape(). The slow path may need the buffer offset too. A zero-offset case in the new test would help confirm it.

if offset != 0:
bank_data = bank_data[offset : (offset + self.width * self.height)]
band_arr = bank_data.reshape(self.height, self.width)
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47 changes: 47 additions & 0 deletions python/tests/raster/test_sample_model.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.

import numpy as np

from sedona.spark.raster.data_buffer import DataBuffer
from sedona.spark.raster.sample_model import ComponentSampleModel


def test_component_sample_model_fast_path_uses_band_offsets() -> None:
sample_model = ComponentSampleModel(
DataBuffer.TYPE_INT,
2,
2,
1,
2,
[1, 0],
[3, 1],
)
data_buffer = DataBuffer(
DataBuffer.TYPE_INT,
[
np.array([10, 11, 12, 13, 14, 15, 16]),
np.array([20, 21, 22, 23, 24, 25, 26]),
],
7,
[0, 0],
)

np.testing.assert_array_equal(
sample_model.as_numpy(data_buffer),
np.array([[[23, 24], [25, 26]], [[11, 12], [13, 14]]]),
)
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