Implement hodograph_samples() to return sorted samples w/heights

lib/xmet/hodograph.py

@@ -33,6 +33,9 @@ class Hodograph():
             box_height = max_y - min_y
             box        = max(box_width, box_height) * 1.5
 
+            if box == 0:
+                box = 1.5
+
             #
             # Ensure the data points are centered within the hodograph
             # viewbox.
@@ -286,7 +289,11 @@ class Hodograph():
             cr.rectangle(offset + x, y + width * 1.5, width, width)
             cr.stroke()
 
-            text    = "%dm" % (height) if height < 1000 else "%dkm" % (height /1000)
+            if height < 1000:
+                text = "%dm" % (height)
+            else:
+                text = "%dkm" % (int(height / 1000.0))
+
             extents = cr.text_extents(text)
 
             cr.move_to(offset + x - extents.width / 4, y + 3.5*width)

lib/xmet/sounding.py

@@ -285,6 +285,11 @@ class Sounding(DatabaseTable):
 
         return wind_speed_dir(shear_u / levels, shear_v / levels)
 
+    def hodograph_samples(self) -> list[SoundingSample]:
+        samples = filter(lambda s: s.height is not None, self.samples)
+
+        return sorted(samples, key=lambda s: s.height)
+
 def between(n, a, b):
     return n > a and n < b