DOC: Make temperature scale example use a closure for easier reusability

ngoldbaum · ngoldbaum · commit 58f1813989f8 · 2019-06-20T17:02:09.000-04:00
diff --git a/examples/subplots_axes_and_figures/fahrenheit_celsius_scales.py b/examples/subplots_axes_and_figures/fahrenheit_celsius_scales.py
@@ -13,29 +13,34 @@
 
 def fahrenheit2celsius(temp):
     """
-    Returns temperature in Celsius.
+    Returns temperature in Celsius given Fahrenheit temperature.
     """
     return (5. / 9.) * (temp - 32)
 
 
-def convert_ax_c_to_celsius(ax_f):
-    """
-    Update second axis according with first axis.
-    """
-    y1, y2 = ax_f.get_ylim()
-    ax_c.set_ylim(fahrenheit2celsius(y1), fahrenheit2celsius(y2))
-    ax_c.figure.canvas.draw()
+def make_plot():
+
+    # Define a closure function to register as a callback
+    def convert_ax_c_to_celsius(ax_f):
+        """
+        Update second axis according with first axis.
+        """
+        y1, y2 = ax_f.get_ylim()
+        ax_c.set_ylim(fahrenheit2celsius(y1), fahrenheit2celsius(y2))
+        ax_c.figure.canvas.draw()
+
+    fig, ax_f = plt.subplots()
+    ax_c = ax_f.twinx()
 
-fig, ax_f = plt.subplots()
-ax_c = ax_f.twinx()
+    # automatically update ylim of ax2 when ylim of ax1 changes.
+    ax_f.callbacks.connect("ylim_changed", convert_ax_c_to_celsius)
+    ax_f.plot(np.linspace(-40, 120, 100))
+    ax_f.set_xlim(0, 100)
 
-# automatically update ylim of ax2 when ylim of ax1 changes.
-ax_f.callbacks.connect("ylim_changed", convert_ax_c_to_celsius)
-ax_f.plot(np.linspace(-40, 120, 100))
-ax_f.set_xlim(0, 100)
+    ax_f.set_title('Two scales: Fahrenheit and Celsius')
+    ax_f.set_ylabel('Fahrenheit')
+    ax_c.set_ylabel('Celsius')
 
-ax_f.set_title('Two scales: Fahrenheit and Celsius')
-ax_f.set_ylabel('Fahrenheit')
-ax_c.set_ylabel('Celsius')
+    plt.show()
 
-plt.show()
+make_plot()
