Simplify the LineCollection example

Inspired by but independent of matplotlib#27871.

This example is much simpler, but conveys the same LineCollection
aspects - with the exception of not using masked arrays. But I argue
that this first example should be simple and using masked arrays rather
distracts from the core aspects of LineCollection.

galleries/examples/shapes_and_collections/line_collection.py

@@ -3,43 +3,33 @@
 Plotting multiple lines with a LineCollection
 =============================================
 
-Matplotlib can efficiently draw multiple lines at once using a
-`~.LineCollection`, as showcased below.
+Matplotlib can efficiently draw multiple lines at once using a `~.LineCollection`.
 """
 
 import matplotlib.pyplot as plt
 import numpy as np
 
 from matplotlib.collections import LineCollection
 
-x = np.arange(100)
-# Here are many sets of y to plot vs. x
-ys = x[:50, np.newaxis] + x[np.newaxis, :]
+colors = ['violet', 'blue', 'green', 'yellow', 'orange', 'red']
 
-segs = np.zeros((50, 100, 2))
-segs[:, :, 1] = ys
-segs[:, :, 0] = x
+# create a list of half-circles with varying radii
+theta = np.linspace(0, np.pi, 36)
+radii = np.linspace(4, 5, num=len(colors))
+arcs = [np.column_stack([r * np.cos(theta), r * np.sin(theta)]) for r in radii]
 
-# Mask some values to test masked array support:
-segs = np.ma.masked_where((segs > 50) & (segs < 60), segs)
+fig, ax = plt.subplots(figsize=(6, 3))
 
-# We need to set the plot limits, they will not autoscale
-fig, ax = plt.subplots()
-ax.set_xlim(x.min(), x.max())
-ax.set_ylim(ys.min(), ys.max())
+# create a LineCollection with the half-circles
+# its properties can be set per line by passing a sequence (here used for *colors*)
+# or they can be set for all lines by passing a scalar (here used for *linewidths*)
+line_collection = LineCollection(arcs, colors=colors, linewidths=4)
+ax.add_collection(line_collection)
 
-# *colors* is sequence of rgba tuples.
-# *linestyle* is a string or dash tuple. Legal string values are
-# solid|dashed|dashdot|dotted.  The dash tuple is (offset, onoffseq) where
-# onoffseq is an even length tuple of on and off ink in points.  If linestyle
-# is omitted, 'solid' is used.
-# See `matplotlib.collections.LineCollection` for more information.
-colors = plt.rcParams['axes.prop_cycle'].by_key()['color']
+# set the axes limits manually because Collections do not take part in autoscaling
+ax.set_xlim(-6, 6)
+ax.set_ylim(0, 6)
 
-line_segments = LineCollection(segs, linewidths=(0.5, 1, 1.5, 2),
-                               colors=colors, linestyle='solid')
-ax.add_collection(line_segments)
-ax.set_title('Line collection with masked arrays')
 plt.show()
 
 # %%