Allow lazy execution of the reprojection method #1082
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The following things are missing, which I'd like to further implement:
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This function called in |
This now works in a lazy manner. |
CHANGES.md
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| ### Fixes | ||
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| * The function `resampling_in_space` now operates lazily and support chunk-wise, |
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| * The function `resampling_in_space` now operates lazily and support chunk-wise, | |
| * The function `resampling_in_space` now operates lazily and supports chunk-wise, |
| @@ -196,7 +196,7 @@ def resample_in_space( | |||
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| downscaled_dataset = resample_dataset( | |||
| source_ds, | |||
| ((x_scale, 1, 0), (1, y_scale, 0)), | |||
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Why is the scale factor now inverted in this case?
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I came across this through an example and realized that it should be inverted. It is not covered by any test.
The code applies these steps if 0.95 target_gm.x_res > source_gm.x_res, meaning that the source has a finer resolution than the target resolution. If this is the case the source dataset shall be resampled to a coarser grid, which has a similar resolution like the target grid. But since x_scale < 0.95, the grid will be even finer. However, the inverse downsamples the source dataset to the desired resolution.
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However, I forot to change it in the if source_gm.is_regular:, which I will correct for in the next push
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I think line 184 (downscaled_gm = source_gm.scale((x_scale, y_scale)) ) also needs this inversion.
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| if other._xy_coords is None: | ||
| _ = other.xy_coords |
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From code inspection and context, I realize that we're forcing initialization of other._xy_coords here, but a brief explanatory comment would be welcome :)
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| # Source has higher resolution than target. | ||
| # Downscale first, then rectify | ||
| if source_gm.is_regular: | ||
| # If source is regular | ||
| downscaled_gm = source_gm.scale((x_scale, y_scale)) | ||
| downscaled_dataset = resample_dataset( | ||
| source_ds, | ||
| ((x_scale, 1, 0), (1, y_scale, 0)), | ||
| size=downscaled_gm.size, | ||
| tile_size=source_gm.tile_size, | ||
| xy_dim_names=source_gm.xy_dim_names, | ||
| var_configs=var_configs, | ||
| ) |
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The code does not go into this if case. If the source_gm is regular, an affine transformation will be performed in line 151.
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| # Source has higher resolution than target. | ||
| # Downscale first, then rectify | ||
| if source_gm.is_regular: | ||
| # If source is regular | ||
| downscaled_gm = source_gm.scale((x_scale, y_scale)) | ||
| downscaled_dataset = resample_dataset( | ||
| source_ds, | ||
| ((x_scale, 1, 0), (1, y_scale, 0)), | ||
| size=downscaled_gm.size, | ||
| tile_size=source_gm.tile_size, | ||
| xy_dim_names=source_gm.xy_dim_names, | ||
| var_configs=var_configs, | ||
| ) |
Co-authored-by: Norman Fomferra <norman.fomferra@brockmann-consult.de>
Co-authored-by: Norman Fomferra <norman.fomferra@brockmann-consult.de>
Co-authored-by: Norman Fomferra <norman.fomferra@brockmann-consult.de>
Closes #1079
Allow lazy execution of the
resampling_in_spacemethod. Following changes have been implemented:xy_reshas been added to the functiontransform_grid_mapping()inxcube/core/gridmapping transform, which allows the user to set the resolution of the new gridmapping, which speeds up the method, because the estimation of the spatial resolution takes a lot of time if reprojection is required.tile_sizeis specified for the resampled grid mapping, it defaults to thetile_sizeof the source grid mapping, improving the user-friendliness of resampling and reprojection.Checklist:
New/modified features documented indocs/source/*CHANGES.md