Add satpy cf reader files

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>

satpy/etc/readers/satpy_cf_nc.yaml

@@ -0,0 +1,14 @@
+reader:
+    name: satpy_cf_nc
+    description: Reader for Satpy's NC/CF files 
+    reader: !!python/name:satpy.readers.yaml_reader.FileYAMLReader
+    sensors: [many]
+    default_channels: []
+
+#datasets:
+
+file_types:
+    graphic:
+        file_reader: !!python/name:satpy.readers.satpy_cf_nc.SatpyCFFileHandler
+        file_patterns:
+         - '{platform_name}-{sensor}-{start_time:%Y%m%d%H%M%S}-{end_time:%Y%m%d%H%M%S}.nc'

satpy/readers/satpy_cf_nc.py

@@ -0,0 +1,112 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Copyright (c) 2019 Satpy developers
+#
+# This file is part of satpy.
+#
+# satpy is free software: you can redistribute it and/or modify it under the
+# terms of the GNU General Public License as published by the Free Software
+# Foundation, either version 3 of the License, or (at your option) any later
+# version.
+#
+# satpy is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# satpy.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Reader for Satpy-produced netcdf files (CF writer)."""
+
+from satpy.readers.file_handlers import BaseFileHandler
+import logging
+import xarray as xr
+from satpy import CHUNK_SIZE
+
+logger = logging.getLogger(__name__)
+
+
+class SatpyCFFileHandler(BaseFileHandler):
+    """File handler for Satpy's CF netCDF files."""
+
+    def __init__(self, filename, filename_info, filetype_info):
+        """Initialize file handler."""
+        super().__init__(filename, filename_info, filetype_info)
+        self.engine = None
+
+    @property
+    def start_time(self):
+        """Get start time."""
+        return self.filename_info['start_time']
+
+    @property
+    def end_time(self):
+        """Get end time."""
+        return self.filename_info.get('end_time', self.start_time)
+
+    @property
+    def sensor(self):
+        """Get sensor."""
+        nc = xr.open_dataset(self.filename, engine=self.engine)
+
+        return nc.attrs['instrument'].replace('/', '-').lower()
+
+    @property
+    def sensor_names(self):
+        """Get sensor set."""
+        return {self.sensor}
+
+    def available_datasets(self, configured_datasets=None):
+        """Add information to configured datasets."""
+        # pass along existing datasets
+        for is_avail, ds_info in (configured_datasets or []):
+            yield is_avail, ds_info
+        nc = xr.open_dataset(self.filename, engine=self.engine)
+        # get dynamic variables known to this file (that we created)
+        for var_name, val in nc.data_vars.items():
+            ds_info = dict(val.attrs)
+            ds_info['file_type'] = self.filetype_info['file_type']
+            ds_info['name'] = var_name
+            try:
+                ds_info['wavelength'] = tuple(ds_info['wavelength'])
+            except KeyError:
+                pass
+            try:
+                try:
+                    ds_info['modifiers'] = tuple(ds_info['modifiers'].split(' '))
+                except AttributeError:
+                    pass
+            except KeyError:
+                pass
+            if var_name not in ['longitude', 'latitude']:
+                ds_info['coordinates'] = ['longitude', 'latitude']
+            yield True, ds_info
+        for var_name, val in nc.coords.items():
+            ds_info = dict(val.attrs)
+            ds_info['file_type'] = self.filetype_info['file_type']
+            ds_info['name'] = var_name
+            ds_info['resolution'] = 742
+            yield True, ds_info
+
+    def get_dataset(self, ds_id, ds_info):
+        """Get dataset."""
+        logger.debug("Getting data for: %s", ds_id.name)
+        nc = xr.open_dataset(self.filename, engine=self.engine,
+                             chunks={'y': CHUNK_SIZE, 'x': CHUNK_SIZE})
+        file_key = ds_info.get('file_key', ds_id.name)
+        data = nc[file_key]
+        if file_key in nc.coords.keys():
+            data = data.drop_vars(list(nc.coords.keys()))
+        try:
+            data.attrs['wavelength'] = tuple(data.attrs['wavelength'])
+        except KeyError:
+            pass
+        try:
+            # FIXME in cf writer: this is not consitent: no modifier is (), modifiers is a string
+            try:
+                ds_info['modifiers'] = tuple(ds_info['modifiers'].split(' '))
+            except AttributeError:
+                pass
+        except KeyError:
+            pass
+        return data