Add wind_u(), wind_v() vector component functions

lib/xmet/hodograph.py

@@ -1,7 +1,7 @@
 import math
 import cairo
 
-from xmet.igra     import IGRAReader
+from xmet.units    import rad, knots
 from xmet.sounding import Sounding
 
 WIND_SPEED_MAX  = 140 # knots
@@ -10,15 +10,6 @@ WIND_SPEED_STEP =  10
 
 WIND_DIR_STEP = 30 # degrees
 
-def radians(degrees: float) -> float:
-    return (degrees + 90) * (math.pi / 180.0)
-
-def degrees(radians: float) -> float:
-    return (radians * (180.0 / math.pi)) - 90
-
-def knots(ms: float) -> float:
-    return ms * 1.944
-
 class Hodograph():
     def __init__(self, width, height):
         self.width   = min(width, height)
@@ -29,8 +20,8 @@ class Hodograph():
     def sample_to_screen(self, wind_speed: dir, wind_dir: float) -> tuple:
         r = self.radius * (wind_speed / WIND_SPEED_MAX)
 
-        x = self.radius + r * math.cos(radians(wind_dir))
+        x = self.radius + r * math.cos(rad(wind_dir))
-        y = self.radius + r * math.sin(radians(wind_dir))
+        y = self.radius + r * math.sin(rad(wind_dir))
 
         if self.extents is None:
             return x, y
@@ -235,8 +226,6 @@ class Hodograph():
         min_x, min_y = self.extents['min']
         max_x, max_y = self.extents['max']
 
-        box = max(max_x - min_x, max_y - min_y)
-
         for sample in self.each_significant_sample(sounding):
             color = self.color(sample.height)
 

lib/xmet/thermo.py

@@ -3,6 +3,7 @@ import math
 from typing import Callable
 
 from xmet.series import Series
+from xmet.units  import rad, kelvin, celsius
 
 LAPSE_RATE_DRY = 9.8 / 1000 # degrees C per km
 
@@ -11,12 +12,6 @@ PRESSURE_MSL  = 1013.25
 PRESSURE_MIN  =  100
 PRESSURE_STEP =   50
 
-def kelvin(c: float) -> float:
-    return 273.15 + c
-
-def celsius(k: float) -> float:
-    return k - 273.15
-
 def virtual_temp(temp: float, dewpoint: float, pressure: float) -> float:
     a = 7.5 * dewpoint
     b = 237.3 + dewpoint
@@ -194,3 +189,9 @@ def follow_saturated_mixing_ratio(temp: float, pressure: float, step: float=1.0)
         p2 -= step
 
     return series
+
+def wind_u(speed: float, direction: float) -> float:
+    return speed * math.cos(rad(direction))
+
+def wind_v(speed: float, direction: float) -> float:
+    return -speed * math.sin(rad(direction))

lib/xmet/units.py

@@ -0,0 +1,16 @@
+import math
+
+def deg(rad: float) -> float:
+    return (rad * (180.0 / math.pi)) - 90
+
+def rad(deg: float) -> float:
+    return (deg + 90) * (math.pi / 180.0)
+
+def knots(ms: float) -> float:
+    return ms * 1.944
+
+def kelvin(c: float) -> float:
+    return 273.15 + c
+
+def celsius(k: float) -> float:
+    return k - 273.15