DOC: update the api example engineering_formatter.py

afvincent · afvincent · commit 07f022d4bebb · 2017-08-25T09:39:45.000-07:00
diff --git a/examples/api/engineering_formatter.py b/examples/api/engineering_formatter.py
@@ -14,13 +14,29 @@
 # Fixing random state for reproducibility
 prng = np.random.RandomState(19680801)
 
-fig, ax = plt.subplots()
-ax.set_xscale('log')
-formatter = EngFormatter(unit='Hz')
-ax.xaxis.set_major_formatter(formatter)
-
+# Create artificial data to plot.
+# The x data span over several decades to demonstrate several SI prefixes.
 xs = np.logspace(1, 9, 100)
-ys = (0.8 + 0.4 * prng.uniform(size=100)) * np.log10(xs)**2
-ax.plot(xs, ys)
+ys = (0.8 + 0.4*prng.uniform(size=100))*np.log10(xs)**2
+
+# Figure width is doubled (2*6.4) to display nicely 2 subplots side by side.
+fig, (ax0, ax1) = plt.subplots(ncols=2, figsize=(12.8, 4.8))
+for ax in (ax0, ax1):
+    ax.set_xscale('log')
+
+# Demo of the default settings, with a user-defined unit label.
+ax0.set_title('Full unit ticklabels, w/ default precision & space sep.')
+formatter0 = EngFormatter(unit='Hz')
+ax0.xaxis.set_major_formatter(formatter0)
+ax0.plot(xs, ys)
+ax0.set_xlabel('Frequency')
+
+# Demo of the options `places` (number of digit after decimal point) and
+# `space_sep` (presence of a space between the number and the prefix/unit).
+ax1.set_title('SI-prefix only ticklabels, 1-digit precision & w/o space sep.')
+formatter1 = EngFormatter(places=1, space_sep=False)
+ax1.xaxis.set_major_formatter(formatter1)
+ax1.plot(xs, ys)
+ax1.set_xlabel('Frequency [Hz]')
 
 plt.show()
