More accurate file size estimate

src/main/python/create_measurements.py

@@ -84,22 +84,18 @@ def estimate_file_size(weather_station_names, num_rows_to_create):
     """
     Tries to estimate how large a file the test data will be
     """
-    max_string = float('-inf')
-    min_string = float('inf')
-    per_record_size = 0
-    record_size_unit = "bytes"
-
-    for station in weather_station_names:
-        if len(station) > max_string:
-            max_string = len(station)
-        if len(station) < min_string:
-            min_string = len(station)
-        per_record_size = ((max_string + min_string * 2) + len(",-123.4")) / 2
-
-    total_file_size = num_rows_to_create * per_record_size
-    human_file_size = convert_bytes(total_file_size)
-
-    return f"Estimated max file size is:  {human_file_size}.\nTrue size is probably much smaller (around half)."
+    total_name_bytes = sum(len(s.encode("utf-8")) for s in weather_station_names)
+    avg_name_bytes = total_name_bytes / float(len(weather_station_names))
+
+    # avg_temp_bytes = sum(len(str(n / 10)) for n in range(-999, 1000)) / 1999
+    avg_temp_bytes = 4.400200100050025
+
+    # add 2 for separator and newline
+    avg_line_length = avg_name_bytes + avg_temp_bytes + 2
+
+    human_file_size = convert_bytes(num_rows_to_create * avg_line_length)
+
+    return f"Estimated max file size is:  {human_file_size}."
 
 
 def build_test_data(weather_station_names, num_rows_to_create):