Merge pull request matplotlib#28014 from anntzer/tl

Improve timeline example.

Author: jklymak

galleries/examples/lines_bars_and_markers/timeline.py

@@ -28,31 +28,28 @@
     data = json.loads(urllib.request.urlopen(url, timeout=1).read().decode())
 
     dates = []
-    names = []
+    releases = []
     for item in data:
         if 'rc' not in item['tag_name'] and 'b' not in item['tag_name']:
             dates.append(item['published_at'].split("T")[0])
-            names.append(item['tag_name'])
-    # Convert date strings (e.g. 2014-10-18) to datetime
-    dates = [datetime.strptime(d, "%Y-%m-%d") for d in dates]
+            releases.append(item['tag_name'].lstrip("v"))
 
 except Exception:
     # In case the above fails, e.g. because of missing internet connection
     # use the following lists as fallback.
-    names = ['v2.2.4', 'v3.0.3', 'v3.0.2', 'v3.0.1', 'v3.0.0', 'v2.2.3',
-             'v2.2.2', 'v2.2.1', 'v2.2.0', 'v2.1.2', 'v2.1.1', 'v2.1.0',
-             'v2.0.2', 'v2.0.1', 'v2.0.0', 'v1.5.3', 'v1.5.2', 'v1.5.1',
-             'v1.5.0', 'v1.4.3', 'v1.4.2', 'v1.4.1', 'v1.4.0']
-
+    releases = ['2.2.4', '3.0.3', '3.0.2', '3.0.1', '3.0.0', '2.2.3',
+                '2.2.2', '2.2.1', '2.2.0', '2.1.2', '2.1.1', '2.1.0',
+                '2.0.2', '2.0.1', '2.0.0', '1.5.3', '1.5.2', '1.5.1',
+                '1.5.0', '1.4.3', '1.4.2', '1.4.1', '1.4.0']
     dates = ['2019-02-26', '2019-02-26', '2018-11-10', '2018-11-10',
              '2018-09-18', '2018-08-10', '2018-03-17', '2018-03-16',
              '2018-03-06', '2018-01-18', '2017-12-10', '2017-10-07',
              '2017-05-10', '2017-05-02', '2017-01-17', '2016-09-09',
              '2016-07-03', '2016-01-10', '2015-10-29', '2015-02-16',
              '2014-10-26', '2014-10-18', '2014-08-26']
 
-    # Convert date strings (e.g. 2014-10-18) to datetime
-    dates = [datetime.strptime(d, "%Y-%m-%d") for d in dates]
+dates = [datetime.strptime(d, "%Y-%m-%d") for d in dates]  # Convert strs to dates.
+dates, releases = zip(*sorted(zip(dates, releases)))  # Sort by increasing date.
 
 # %%
 # Next, we'll create a stem plot with some variation in levels as to
@@ -64,32 +61,45 @@
 #
 # Note that Matplotlib will automatically plot datetime inputs.
 
-
-# Choose some nice levels
-levels = np.tile([-5, 5, -3, 3, -1, 1],
-                 int(np.ceil(len(dates)/6)))[:len(dates)]
-
-# Create figure and plot a stem plot with the date
+# Choose some nice levels: alternate minor releases between top and bottom, and
+# progressievly shorten the stems for bugfix releases.
+levels = []
+major_minor_releases = sorted({release[:3] for release in releases})
+for release in releases:
+    major_minor = release[:3]
+    bugfix = int(release[4])
+    h = 1 + 0.8 * (5 - bugfix)
+    level = h if major_minor_releases.index(major_minor) % 2 == 0 else -h
+    levels.append(level)
+
+# The figure and the axes.
 fig, ax = plt.subplots(figsize=(8.8, 4), layout="constrained")
 ax.set(title="Matplotlib release 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):
-    ax.annotate(r, xy=(d, l),
-                xytext=(-3, np.sign(l)*3), textcoords="offset points",
-                horizontalalignment="right",
-                verticalalignment="bottom" if l > 0 else "top")
-
-# format x-axis with 4-month intervals
-ax.xaxis.set_major_locator(mdates.MonthLocator(interval=4))
-ax.xaxis.set_major_formatter(mdates.DateFormatter("%b %Y"))
-plt.setp(ax.get_xticklabels(), rotation=30, ha="right")
-
-# remove y-axis and spines
+# The vertical stems.
+ax.vlines(dates, 0, levels,
+          color=[("tab:red", 1 if release.endswith(".0") else .5)
+                 for release in releases])
+# The baseline.
+ax.axhline(0, c="black")
+# The markers on the baseline.
+minor_dates = [date for date, release in zip(dates, releases) if release[-1] == '0']
+bugfix_dates = [date for date, release in zip(dates, releases) if release[-1] != '0']
+ax.plot(bugfix_dates, np.zeros_like(bugfix_dates), "ko", mfc="white")
+ax.plot(minor_dates, np.zeros_like(minor_dates), "ko", mfc="tab:red")
+
+# Annotate the lines.
+for date, level, release in zip(dates, levels, releases):
+    ax.annotate(release, xy=(date, level),
+                xytext=(-3, np.sign(level)*3), textcoords="offset points",
+                verticalalignment="bottom" if level > 0 else "top",
+                weight="bold" if release.endswith(".0") else "normal",
+                bbox=dict(boxstyle='square', pad=0, lw=0, fc=(1, 1, 1, 0.7)))
+
+ax.yaxis.set(major_locator=mdates.YearLocator(),
+             major_formatter=mdates.DateFormatter("%Y"))
+
+# Remove the y-axis and some spines.
 ax.yaxis.set_visible(False)
 ax.spines[["left", "top", "right"]].set_visible(False)