Make the function `date_index` more meaningful

Convert_Matlab/overlap_v6.py

@@ -10,13 +10,12 @@ import datetime
 import csv
 import sys
 
-def date_index(k):
-    """Compute the number of days since Jan 1st 1950, given the subscript
-    index in date_num.
+def date_index(date_num):
+    """Convert Matlab serial date number to number of days since Jan 1st
+    1950.
 
     """
-    date = datetime.date.fromordinal(date_num[k] - 366) - datetime.date(1950,
-                                                                        1, 1)
+    date = datetime.date.fromordinal(date_num - 366) - datetime.date(1950, 1, 1)
     return date.days
 
 def convert_id(node_index):
@@ -26,7 +25,7 @@ def convert_id(node_index):
     """
     k = (node_index - 1) // n_max
     eddy_index = node_index - k * n_max
-    return date_index(k), eddy_index
+    return date_index(date_num[k]), eddy_index
 
 orientation = sys.argv[1] # "cyclo" or "anti"
 id_child = sio.loadmat(f"id_child_{orientation}.mat", squeeze_me=True)\
@@ -46,7 +45,7 @@ with open(f"edgelist_{orientation}.csv", "w", newline = '') as edgelist:
     writer.writerow(["k1", "i1", "k2", "i2"])
 
     for k1 in range(n_dates):
-        d1 = date_index(k1)
+        d1 = date_index(date_num[k1])
 
         for i1, id_child_1 in enumerate(id_child[:n_eddies[k1], k1]):
             e1 = i1 + 1