From a23df029d3d7b2c9ac9f5d63a8c63e04c3eb015b Mon Sep 17 00:00:00 2001
From: PennyHow <pho@geus.dk>
Date: Mon, 12 Aug 2024 12:08:38 -0100
Subject: [PATCH] Gap filling step added

---
 src/pypromice/process/L1toL2.py | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/pypromice/process/L1toL2.py b/src/pypromice/process/L1toL2.py
index c8b32bbc..c1bf3969 100644
--- a/src/pypromice/process/L1toL2.py
+++ b/src/pypromice/process/L1toL2.py
@@ -217,6 +217,7 @@ def toL2(
     
 
     ds = clip_values(ds, vars_df)
+    ds = fill_gaps(ds)
     return ds
 
 
@@ -770,6 +771,35 @@ def calcCorrectionFactor(Declination_rad, phi_sensor_rad, theta_sensor_rad,
 
     return CorFac_all
 
+def fill_gaps(ds):
+    '''Fill data gaps with nan values
+    
+    Parameters
+    ----------
+    ds : xarray.Dataset
+        Data set to gap fill
+    
+    Returns
+    -------
+    ds_filled : xarray.Dataset
+        Gap-filled dataset
+    '''    
+    # Determine time range of dataset
+    min_date = ds.to_dataframe().index.min()
+    max_date = ds.to_dataframe().index.max()
+    
+    # Determine common time interval
+    time_diffs = np.diff(ds['time'].values)
+    common_diff = pd.Timedelta(pd.Series(time_diffs).mode()[0])
+    
+    # Determine gap filled index
+    full_time_range = pd.date_range(start=min_date, 
+                                    end=max_date, 
+                                    freq=common_diff)
+    
+    # Apply gap-fille index to dataset
+    ds_filled = ds.reindex({'time': full_time_range}, fill_value=np.nan)
+    return ds_filled
 
 def _checkSunPos(ds, OKalbedos, sundown, sunonlowerdome, TOA_crit_nopass):
     '''Check sun position