Added a function to create a reference data frame.

toarstats/interface.py

@@ -5,6 +5,7 @@ calculate_statistics - calculate the requested statistics
 """
 
 from toarstats.input_checks import check_input_parameters
+from toarstats.stats_utils import create_reference_data_frame
 
 
 def calculate_statistics(
@@ -104,3 +105,6 @@ def calculate_statistics(
         sampling, statistics, data, metadata, seasons, crops, data_capture,
         datetimes, values, station_lat, station_lon, station_climatic_zone
     )
+    reference_data_frame = create_reference_data_frame(
+        input_parameters.data.index
+    )

toarstats/stats_utils.py

@@ -3,6 +3,7 @@
 This module contains the following functions:
 aot40stat - evaluate the sum of values above the given threshold
 calc_data_capture - calculate the data capture fraction
+create_reference_data_frame - create a reference data frame
 dma8_processor - calculate the daily maximum 8-hour running mean
 get_elevation_angle - calculate the solar elevation angle
 get_growing_season - get the correct season name
@@ -99,6 +100,23 @@ def calc_data_capture(df, dfref, sampling, how, mincount=0, minfrac=None,
     return dfres
 
 
+def create_reference_data_frame(index):
+    """Create a reference data frame.
+
+    :param index: the given index
+
+    :return: A data frame with a date range spanning from the beginning
+             of the earliest given year to the ending of the latest
+             given year and filled with zeros
+    """
+    min_date = index.min()
+    max_date = index.max()
+    start_date = f"{min_date.year}-01-01 00:{min_date.minute}"
+    end_date = f"{max_date.year}-12-31 23:{max_date.minute}"
+    reference_index = pd.date_range(start=start_date, end=end_date, freq="H")
+    return pd.DataFrame(np.zeros(reference_index.size), index=reference_index)
+
+
 def dma8_processor(df, dfref, mtype, metadata, seasons, data_capture, tshift=0,
                    hours=[0, 23], dname="", strict=False, average=False):
     """Calculate the daily maximum 8-hour running mean.