Use vlines() and plot(), not stem(), in timeline example.

anntzer · anntzer · commit d4ba4e7a2de4 · 2020-02-11T22:33:47.000+01:00
It's actually easier (IMO...) to achieve the desired result by
combining vlines() and plot() is actually much easier rather than by
using stem() and then fiddling with the artists.

(The visual result is unchanged.)
diff --git a/examples/lines_bars_and_markers/timeline.py b/examples/lines_bars_and_markers/timeline.py
@@ -53,10 +53,10 @@
     dates = [datetime.strptime(d, "%Y-%m-%d") for d in dates]
 
 ##############################################################################
-# Next, we'll create a `~.Axes.stem` plot with some variation in levels as to
-# distinguish even close-by events. In contrast to a usual stem plot, we will
-# shift the markers to the baseline for visual emphasis on the one-dimensional
-# nature of the time line.
+# Next, we'll create a stem plot with some variation in levels as to
+# distinguish even close-by events. We add markers on the baseline for visual
+# emphasis on the one-dimensional nature of the time line.
+#
 # For each event, we add a text label via `~.Axes.annotate`, which is offset
 # in units of points from the tip of the event line.
 #
@@ -71,14 +71,9 @@
 fig, ax = plt.subplots(figsize=(8.8, 4), constrained_layout=True)
 ax.set(title="Matplotlib release dates")
 
-markerline, stemline, baseline = ax.stem(dates, levels,
-                                         linefmt="C3-", basefmt="k-",
-                                         use_line_collection=True)
-
-plt.setp(markerline, mec="k", mfc="w", zorder=3)
-
-# Shift the markers to the baseline by replacing the y-data by zeros.
-markerline.set_ydata(np.zeros(len(dates)))
+ax.vlines(dates, 0, levels, color="tab:red")  # The vertical stems.
+ax.plot(dates, np.zeros_like(dates), "-o",
+        color="k", markerfacecolor="w")  # Baseline and markers on it.
 
 # annotate lines
 for d, l, r in zip(dates, levels, names):
@@ -112,8 +107,8 @@
 # in this example:
 
 import matplotlib
-matplotlib.axes.Axes.stem
 matplotlib.axes.Axes.annotate
+matplotlib.axes.Axes.vlines
 matplotlib.axis.Axis.set_major_locator
 matplotlib.axis.Axis.set_major_formatter
 matplotlib.dates.MonthLocator
