added tick labels from values demo

cammil · cammil · commit 9cba700de6a2 · 2015-09-14T16:04:08.000+01:00
diff --git a/examples/ticks_and_spines/tick_labels_from_values.py b/examples/ticks_and_spines/tick_labels_from_values.py
@@ -0,0 +1,36 @@
+"""
+
+Basic demo showing how to set tick labels to values of a series.
+
+Using ax.set_xticks causes the tick labels to be set on the currently
+chosen ticks. However, you may want to allow matplotlib to dynamically 
+choose the number of ticks and their spacing.
+
+In this case may be better to determine the tick label from the value
+at the tick. The following example shows how to do this.
+
+NB: You may want to combine the solution below with 
+`xaxis.set_major_locator(MaxNLocator(integer=True))` to ensure
+that tick values are always at integer values, and therefore always use
+the appropriate label.
+
+"""
+
+
+
+import matplotlib.pyplot as plt
+from matplotlib.ticker import FuncFormatter
+
+fig = plt.figure()
+ax = fig.add_subplot(111)
+xs = range(26)
+ys = range(26)
+labels = list('abcdefghijklmnopqrstuvwxyz')
+
+def format_fn(tick_val, tick_pos): 
+    return labels[int(tick_val)]
+
+ax.xaxis.set_major_formatter(FuncFormatter(format_fn))
+
+ax.plot(xs, ys)
+plt.show()
