Add plot_dates.py as it is as a Matplotlib example

https://matplotlib.org/3.8.0/gallery/lines_bars_and_markers/timeline.html

datasets/rafael/240424/plot_dates.py

@@ -0,0 +1,74 @@
+from datetime import datetime
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+import matplotlib.dates as mdates
+
+try:
+    # Try to fetch a list of Matplotlib releases and their dates
+    # from https://api.github.com/repos/matplotlib/matplotlib/releases
+    import json
+    import urllib.request
+
+    url = 'https://api.github.com/repos/matplotlib/matplotlib/releases'
+    url += '?per_page=100'
+    data = json.loads(urllib.request.urlopen(url, timeout=1).read().decode())
+
+    dates = []
+    names = []
+    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]
+
+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']
+
+    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]
+
+# 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
+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
+ax.yaxis.set_visible(False)
+ax.spines[["left", "top", "right"]].set_visible(False)
+
+ax.margins(y=0.1)
+plt.show()