Merge pull request matplotlib#5063 from cammil/master

DOC: added tick labels from values demo

Author: tacaswell

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: The MaxNLocator is used here to ensure that the tick
+values take integer values. As such, we need to catch
+any IndexErrors in the format function where we have not
+defined a label for that particular tick
+
+"""
+
+import matplotlib.pyplot as plt
+from matplotlib.ticker import FuncFormatter, MaxNLocator
+fig = plt.figure()
+ax = fig.add_subplot(111)
+xs = range(26)
+ys = range(26)
+labels = list('abcdefghijklmnopqrstuvwxyz')
+
+
+def format_fn(tick_val, tick_pos):
+    if int(tick_val) in xs:
+        return labels[int(tick_val)]
+    else:
+        return ''
+ax.xaxis.set_major_formatter(FuncFormatter(format_fn))
+ax.xaxis.set_major_locator(MaxNLocator(integer=True))
+ax.plot(xs, ys)
+plt.show()