Merge pull request #154 from bmorris3/plot-am

Plot airmass

astroplan/plots/time_dependent.py

@@ -31,6 +31,20 @@ def _secz_to_altitude(secant_z):
     """
     return np.degrees(np.pi/2 - np.arccos(1./secant_z))
 
+
+def _has_twin(ax):
+    """
+    Solution for detecting twin axes built on `ax`. Courtesy of
+    Jake Vanderplas http://stackoverflow.com/a/36209590/1340208
+    """
+    for other_ax in ax.figure.axes:
+        if other_ax is ax:
+            continue
+        if other_ax.bbox.bounds == ax.bbox.bounds:
+            return True
+    return False
+
+
 def plot_airmass(target, observer, time, ax=None, style_kwargs=None,
                  style_sheet=None, brightness_shading=False,
                  altitude_yaxis=False):
@@ -171,7 +185,7 @@ def plot_airmass(target, observer, time, ax=None, style_kwargs=None,
     ax.set_ylabel("Airmass")
     ax.set_xlabel("Time from {0} [UTC]".format(min(time).datetime.date()))
 
-    if altitude_yaxis:
+    if altitude_yaxis and not _has_twin(ax):
         altitude_ticks = np.array([90, 60, 50, 40, 30, 20])
         airmass_ticks = 1./np.cos(np.radians(90 - altitude_ticks))