Develop VIIRS

monetio/sat/_viirs_l2_mm.py

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+import logging
+import sys
+from collections import OrderedDict
+from datetime import datetime, timezone
+from glob import glob
+
+import numpy as np
+import xarray as xr
+
+
+def read_dataset(fname, variable_dict):
+    """
+    Parameters
+    ----------
+    fname : str
+        Input file path.
+
+    Returns
+    -------
+    xarray.Dataset
+    """
+    print("reading " + fname)
+
+    ds_subset = xr.Dataset()
+
+    ds = xr.open_dataset(fname)
+    # print(ds)
+
+    for varname in variable_dict:
+        print(varname)
+        values = ds[varname].values
+        if "scale" in variable_dict[varname]:
+            values = variable_dict[varname]["scale"] * values
+        if "minimum" in variable_dict[varname]:
+            minimum = variable_dict[varname]["minimum"]
+            values[values < minimum] = np.nan
+        if "maximum" in variable_dict[varname]:
+            maximum = variable_dict[varname]["maximum"]
+            values[values > maximum] = np.nan
+        ds_subset[varname] = xr.DataArray(values)
+        if "quality_flag" in variable_dict[varname]:
+            ds_subset.attrs["quality_flag"] = varname
+            ds_subset.attrs["quality_thresh"] = variable_dict[varname]["quality_flag"]
+
+    return ds_subset
+
+
+def apply_quality_flag(ds):
+    """
+    Parameters
+    ----------
+    ds : xarray.Dataset
+    """
+    if "quality_flag" in ds.attrs:
+        quality_flag = ds[ds.attrs["quality_flag"]]
+        quality_thresh = ds.attrs["quality_thresh"]
+        for varname in ds:
+            if varname != ds.attrs["quality_flag"]:
+                logging.debug(varname)
+                values = ds[varname].values
+                values[quality_flag >= quality_thresh] = np.nan
+                ds[varname].values = values
+
+
+def read_mfdataset(fnames, variable_dict, debug=False):
+    """
+    Parameters
+    ----------
+    fnames : str
+        Regular expression for input file paths.
+
+    Returns
+    -------
+    xarray.Dataset
+    """
+    if debug:
+        logging_level = logging.DEBUG
+        logging.basicConfig(stream=sys.stdout, level=logging_level)
+
+    if isinstance(fnames, str):
+        files = sorted(glob(fnames))
+    else:
+        files = fnames
+
+    granules = OrderedDict()
+
+    for file in files:
+        granule = read_dataset(file, variable_dict)
+        apply_quality_flag(granule)
+        granule_str = file.split("/")[-1]
+        granule_info = granule_str.split(".")
+        datetime_str = granule_info[1][1:] + granule_info[2]
+        granules[datetime_str] = granule
+
+    return granules