add is_elapsed checker

Author: lily-tomkovic-DWR

schimpy/model_time.py

@@ -428,17 +428,26 @@ def elapsed_to_timestamp(input, time_basis, elapsed_unit="s"):
     return out_df
 
 
-def read_th(input, time_basis=None, to_timestamp=True, elapsed_unit="s"):
-    """Read input file and return dataframe.
-    Automatically converts to timestamp if time_basis is supplied unless to_timestamp is False
+def is_elapsed(input):
+    """Check whether the input file is 'elapsed' or 'timestamped'.
+    Uses the first line of the file to determine this.
+    If there are any non-numeric characters then that's a timestamped file and is_elapsed would return False
     """
 
-    # check if first line contains headers (and thus is elapsed)
     with open(input, "r") as f:
         first_line = f.readline().strip()
     is_elapsed = all(re.match(r"^[-+]?\d*\.?\d+$", s) for s in first_line.split())
 
-    if is_elapsed:
+    return is_elapsed
+
+
+def read_th(input, time_basis=None, to_timestamp=True, elapsed_unit="s"):
+    """Read input file and return dataframe.
+    Automatically converts to timestamp if time_basis is supplied unless to_timestamp is False
+    """
+
+    # check if first line contains headers (and thus is elapsed)s
+    if is_elapsed(input):
         # read elapsed file
         if time_basis is None:
             raise ValueError(