Add flash age compositor for li instruments

satpy/composites/lightning.py

@@ -0,0 +1,99 @@
+#!/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/>.
+"""Composite classes for the LI instrument."""
+
+import logging
+
+import numpy as np
+import xarray as xr
+
+from satpy.composites import CompositeBase
+
+LOG = logging.getLogger(__name__)
+
+
+class LightningTimeCompositor(CompositeBase):
+      """Class used to create the flash_age compositor usefull for lighting event visualisation.
+
+      The datas used are dates related to the lightning event that should be normalised between
+      0 and 1. The value 1 corresponds to the latest lightning event and the value 0 corresponds
+      to the latest lightning event - time_range. The time_range is defined in the satpy/etc/composites/li.yaml
+      and is in minutes.
+      """
+      def __init__(self, name, prerequisites=None, optional_prerequisites=None, **kwargs):
+          """Initialisation of the class."""
+          self.name = name
+          super().__init__(name, prerequisites, optional_prerequisites, **kwargs)
+          # Get the time_range which is in minute
+          self.time_range = self.attrs["time_range"]
+          self.standard_name = self.attrs["standard_name"]
+
+      def _normalize_time(self,data:xr.DataArray,attrs:dict)->xr.DataArray:
+          """Normalised the time in the range between [end_time,end_time - time_range].
+
+          The range of the normalised data is between 0 and 1 where 0 corresponds to the date end_time - time_range
+          and 1 to the end_time. Where end_times represent the latest lightning event and time_range is the range of
+          time you want to see the event.The dates that are earlier to end_time - time_range are removed.
+
+          Args:
+              data (xr.DataArray): datas containing dates to be normalised
+              attrs (dict): Attributes suited to the flash_age composite
+
+          Returns:
+              xr.DataArray: Normalised time
+          """
+          # Compute the maximum time value
+          end_time = data.max().values
+          # Compute the minimum time value based on the time range
+          begin_time = end_time - np.timedelta64(self.time_range, "m")
+          # Drop values that are bellow begin_time
+          data = data.where(data > begin_time, drop=True)
+          # Normalize the time values
+          normalized_data = (data - begin_time) / (end_time - begin_time)
+          # Ensure the result is still an xarray.DataArray
+          return xr.DataArray(normalized_data, dims=data.dims, coords=data.coords,attrs=attrs)
+
+
+      @staticmethod
+      def _update_missing_metadata(existing_attrs, new_attrs):
+          for key, val in new_attrs.items():
+              if key not in existing_attrs and val is not None:
+                  existing_attrs[key] = val
+
+      def _redefine_metadata(self,attrs:dict)->dict:
+          """Modify the standard_name and name metadatas.
+
+          Args:
+              attrs (dict): data's attributes
+
+          Returns:
+              dict: atualised attributes
+          """
+          attrs["name"] = self.standard_name
+          attrs["standard_name"] =self.standard_name
+          # Attributes to describe the values range
+          return attrs
+
+
+      def __call__(self,projectables, nonprojectables=None, **attrs):
+          """Normalise the dates."""
+          data = projectables[0]
+          new_attrs = data.attrs.copy()
+          self._update_missing_metadata(new_attrs, attrs)
+          new_attrs = self._redefine_metadata(new_attrs)
+          return self._normalize_time(data,new_attrs)

satpy/etc/composites/li.yaml

@@ -10,69 +10,78 @@ composites:
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: acc_flash
     prerequisites:
-    - flash_accumulation
+      - flash_accumulation
   acc_flash_alpha:
     description: Composite to colorise the AF product using the flash accumulation with transparency
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: acc_flash_alpha
     prerequisites:
-    - flash_accumulation
+      - flash_accumulation
 
   acc_flash_area:
     description: Composite to colorise the AFA product using the flash area
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: acc_flash_area
     prerequisites:
-    - accumulated_flash_area
+      - accumulated_flash_area
   acc_flash_area_alpha:
     description: Composite to colorise the AFA product using the flash area with transparency
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: acc_flash_area_alpha
     prerequisites:
-    - accumulated_flash_area
+      - accumulated_flash_area
 
   acc_flash_radiance:
     description: Composite to colorise the AFR product using the flash radiance
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance
     prerequisites:
-    - flash_radiance
+      - flash_radiance
   acc_flash_radiance_alpha:
     description: Composite to colorise the AFR product using the flash radiance with transparency
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance_alpha
     prerequisites:
-    - flash_radiance
+      - flash_radiance
 
   flash_radiance:
     description: Composite to colorise the LFL product using the flash radiance
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance
     prerequisites:
-    - radiance
+      - radiance
   flash_radiance_alpha:
     description: Composite to colorise the LFL product using the flash radiance with transparency
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance_alpha
     prerequisites:
-    - radiance
+      - radiance
 
   group_radiance:
     description: Composite to colorise the LGR product using the flash radiance
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance
     prerequisites:
-    - radiance
+      - radiance
   group_radiance_alpha:
     description: Composite to colorise the LGR product using the flash radiance with transparency
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: lightning_radiance_alpha
     prerequisites:
-    - radiance
+      - radiance
 
   # DEPRECATED, USE acc_flash_area INSTEAD
   flash_area:
     compositor: !!python/name:satpy.composites.SingleBandCompositor
     standard_name: acc_flash_area
     prerequisites:
-    - accumulated_flash_area
+      - accumulated_flash_area
+
+  flash_age:
+    description: Composite to colorise the LFL product using the flash time
+    compositor: !!python/name:satpy.composites.lightning.LightningTimeCompositor
+    standard_name: lightning_time
+    time_range: 60 # range for colormap in minutes
+    reference_time: end_time
+    prerequisites:
+      - flash_time

satpy/etc/enhancements/li.yaml

@@ -1,60 +1,84 @@
 enhancements:
-# note that the colormap parameters are tuned for 5 minutes of files accumulation
-# these are tentative recipes that will need to be further tuned as we gain experience with LI data
+  # note that the colormap parameters are tuned for 5 minutes of files accumulation
+  # these are tentative recipes that will need to be further tuned as we gain experience with LI data
 
   acc_flash:
     standard_name: acc_flash
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 5}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - { colors: ylorrd, min_value: 0, max_value: 5 }
 
   acc_flash_alpha:
     standard_name: acc_flash_alpha
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 5,
-           min_alpha: 120, max_alpha: 180}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - {
+                colors: ylorrd,
+                min_value: 0,
+                max_value: 5,
+                min_alpha: 120,
+                max_alpha: 180,
+              }
 
   acc_flash_area:
     standard_name: acc_flash_area
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 20}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - { colors: ylorrd, min_value: 0, max_value: 20 }
 
   acc_flash_area_alpha:
     standard_name: acc_flash_area_alpha
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 20,
-           min_alpha: 120, max_alpha: 180}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - {
+                colors: ylorrd,
+                min_value: 0,
+                max_value: 20,
+                min_alpha: 120,
+                max_alpha: 180,
+              }
 
   lightning_radiance:
     standard_name: lightning_radiance
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 1000}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - { colors: ylorrd, min_value: 0, max_value: 1000 }
 
   lightning_radiance_alpha:
     standard_name: lightning_radiance_alpha
     operations:
-    - name: colorize
-      method: !!python/name:satpy.enhancements.colorize
-      kwargs:
-        palettes:
-        - {colors: ylorrd, min_value: 0, max_value: 1000,
-           min_alpha: 120, max_alpha: 180}
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - {
+                colors: ylorrd,
+                min_value: 0,
+                max_value: 1000,
+                min_alpha: 120,
+                max_alpha: 180,
+              }
+
+  lightning_time:
+    standard_name: lightning_time
+    operations:
+      - name: colorize
+        method: !!python/name:satpy.enhancements.colorize
+        kwargs:
+          palettes:
+            - { colors: ylorrd, min_value: 0, max_value: 1 }