def _slice_datasets(self, dataset_ids, slice_key, new_area, area_only=True):
"""Slice scene in-place for the datasets specified."""
new_datasets = {}
datasets = (self[ds_id] for ds_id in dataset_ids)
for ds, parent_ds in dataset_walker(datasets):
ds_id = DatasetID.from_dict(ds.attrs)
# handle ancillary variables
pres = None
if parent_ds is not None:
pres = new_datasets[DatasetID.from_dict(parent_ds.attrs)]
if ds_id in new_datasets:
replace_anc(ds, pres)
continue
if area_only and ds.attrs.get('area') is None:
new_datasets[ds_id] = ds
replace_anc(ds, pres)
continue
if not isinstance(slice_key, dict):
# match dimension name to slice object
key = dict(zip(ds.dims, slice_key))
else:
key = slice_key
new_ds = ds.isel(**key)
if new_area is not None:
new_ds.attrs['area'] = new_area
new_datasets[ds_id] = new_ds
if parent_ds is None:
# don't use `__setitem__` because we don't want this to
# affect the existing wishlist/dep tree
self.datasets[ds_id] = new_ds
else:
replace_anc(new_ds, pres)
def _resampled_scene(self, new_scn, destination_area, **resample_kwargs):
"""Resample `datasets` to the `destination` area."""
new_datasets = {}
datasets = list(new_scn.datasets.values())
max_area = None
if isinstance(destination_area, (str, six.text_type)):
destination_area = get_area_def(destination_area)
if hasattr(destination_area, 'freeze'):
try:
max_area = new_scn.max_area()
destination_area = destination_area.freeze(max_area)
except ValueError:
raise ValueError("No dataset areas available to freeze "
"DynamicAreaDefinition.")
resamplers = {}
for dataset, parent_dataset in dataset_walker(datasets):
ds_id = DatasetID.from_dict(dataset.attrs)
pres = None
if parent_dataset is not None:
pres = new_datasets[DatasetID.from_dict(parent_dataset.attrs)]
if ds_id in new_datasets:
replace_anc(dataset, pres)
continue
if dataset.attrs.get('area') is None:
if parent_dataset is None:
new_scn.datasets[ds_id] = dataset
else:
replace_anc(dataset, pres)
continue
LOG.debug("Resampling %s", ds_id)
source_area = dataset.attrs['area']
try:
slice_x, slice_y = source_area.get_area_slices(
destination_area)
source_area = source_area[slice_y, slice_x]
dataset = dataset.isel(x=slice_x, y=slice_y)
assert ('x', source_area.x_size) in dataset.sizes.items()
assert ('y', source_area.y_size) in dataset.sizes.items()
dataset.attrs['area'] = source_area
except NotImplementedError:
LOG.info("Not reducing data before resampling.")
if source_area not in resamplers:
key, resampler = prepare_resampler(source_area,
destination_area,
**resample_kwargs)
resamplers[source_area] = resampler
self.resamplers[key] = resampler
kwargs = resample_kwargs.copy()
kwargs['resampler'] = resamplers[source_area]
res = resample_dataset(dataset, destination_area, **kwargs)
new_datasets[ds_id] = res
if parent_dataset is None:
new_scn.datasets[ds_id] = res
else:
replace_anc(res, pres)
