Move data spec definitions to new module

data_spec.py

+"""Define `asccol` data specifications."""
+
+import math
+
+import asccol
+
+
+def simple_time(s):
+    """Convert an HHMM string to an (H, M) tuple."""
+    hhmm = int(s)
+    return divmod(hhmm, 100)
+
+
+def filtered_int(s):
+    """Like int, but ignore the special value 999."""
+    val = int(s)
+    return val if val != 999 else math.nan
+
+
+def filtered_float(s):
+    """Like float, but ignore the special values 444.0, 99.9, etc."""
+    val = float(s)
+    return val if val not in (444.0, 99.9, 999.9, 9999.9) else math.nan
+
+
+ONE_HOUR = asccol.DataSpec(
+    leading=2,  # 2 lines to delete
+    cols=(
+        ('year', int, 4),  # name, type (converter function), width
+        ('jdate', int, 4),
+        ('month', int, 3),
+        ('day', int, 3),
+        ('time', simple_time, 5),
+        ('temp', filtered_float, 7),
+        ('pressure', filtered_float, 7),
+        ('wind_speed', filtered_float, 7),
+        ('wind_dir', filtered_float, 7),
+        ('rel_hum', filtered_float, 7),
+        ('delta_t', filtered_float, 7),
+    ),
+)
+SOUTH_POLE = asccol.DataSpec(
+    cols=(
+        ('year', int, 5),
+        ('month', int, 5),
+        ('day', int, 5),
+        ('time', simple_time, 5),
+        ('wind_dir', filtered_int, 4),
+        ('wind_speed', filtered_float, 6),
+        ('visibility', filtered_int, 7),
+        ('temp', filtered_float, 7),
+        ('pressure', filtered_float, 7),
+    ),
+)

visualizer.py

 import datetime
 from io import BytesIO
 import json
-import math
 from types import SimpleNamespace
 from urllib.request import urlopen
 
@@ -13,6 +12,8 @@ import matplotlib.pyplot as plt
 import numpy as np
 from pyld import jsonld
 
+import data_spec
+
 Measurement = make_dataclass('Measurement', ['url_name', 'field', 'title'])
 measurements = {m.url_name: m for m in (
     Measurement('temperature', 1, 'Temperature (C)'),
@@ -23,55 +24,6 @@ measurements = {m.url_name: m for m in (
 ACCESS_URL = 'http://www.w3.org/ns/dcat#accessURL'
 DISTRIBUTION = 'http://www.w3.org/ns/dcat#Distribution'
 
-
-def simple_time(s):
-    """Convert an HHMM string to an (H, M) tuple."""
-    hhmm = int(s)
-    return divmod(hhmm, 100)
-
-
-def filtered_int(s):
-    """Like int, but ignore the special value 999."""
-    val = int(s)
-    return val if val != 999 else math.nan
-
-
-def filtered_float(s):
-    """Like float, but ignore the special values 444.0, 99.9, etc."""
-    val = float(s)
-    return val if val not in (444.0, 99.9, 999.9, 9999.9) else math.nan
-
-
-ONE_HOUR_DATA = asccol.DataSpec(
-    leading=2,  # 2 lines to delete
-    cols=(
-        ('year', int, 4),  # name, type (converter function), width
-        ('jdate', int, 4),
-        ('month', int, 3),
-        ('day', int, 3),
-        ('time', simple_time, 5),
-        ('temp', filtered_float, 7),
-        ('pressure', filtered_float, 7),
-        ('wind_speed', filtered_float, 7),
-        ('wind_dir', filtered_float, 7),
-        ('rel_hum', filtered_float, 7),
-        ('delta_t', filtered_float, 7),
-    ),
-)
-SOUTH_POLE_DATA = asccol.DataSpec(
-    cols=(
-        ('year', int, 5),
-        ('month', int, 5),
-        ('day', int, 5),
-        ('time', simple_time, 5),
-        ('wind_dir', filtered_int, 4),
-        ('wind_speed', filtered_float, 6),
-        ('visibility', filtered_int, 7),
-        ('temp', filtered_float, 7),
-        ('pressure', filtered_float, 7),
-    ),
-)
-
 app = Flask(__name__)
 
 app.jinja_env.trim_blocks = True
@@ -350,13 +302,13 @@ def get_resources(link):
 
 def read_data(station, year):
     """Fetch data and convert it to a NumPy array."""
+    spec = (data_spec.SOUTH_POLE if station['id'] == 'south-pole'
+            else data_spec.ONE_HOUR)
     data = []
     resource_list = get_resources(get_link(station, year))
     for url in resource_list:
         with urlopen(url) as f:
             lines = map(bytes.decode, f)
-            spec = (SOUTH_POLE_DATA if station['id'] == 'south-pole'
-                    else ONE_HOUR_DATA)
             for row in asccol.parse_data(lines, spec):
                 date = datetime.datetime(row.year, row.month, row.day,
                                          *row.time)