Tweak titles pyplot examples.

In particular, arrange to not capitalize pyplot.  The old titles were
not particularly great (and likely derived automatically from the
filename back when the move to s-g was done).

Also merge the pyplot_text and pyplot_mathtext examples (both examples
actually show both text and mathtext).

Author: anntzer

.flake8

@@ -84,6 +84,7 @@ per-file-ignores =
     tutorials/introductory/quick_start.py: E703
     tutorials/introductory/animation_tutorial.py: E501
     tutorials/text/annotations.py: E402, E501
+    tutorials/text/mathtext.py: E501
     tutorials/text/text_intro.py: E402
     tutorials/text/text_props.py: E501
     tutorials/text/usetex.py: E501

examples/pyplots/axline.py

@@ -10,6 +10,7 @@
 
 `~.axes.Axes.axline` draws infinite straight lines in arbitrary directions.
 """
+
 import numpy as np
 import matplotlib.pyplot as plt
 

examples/pyplots/pyplot_mathtext.py

@@ -1,16 +1,16 @@
 """
-=============
-Pyplot Simple
-=============
+===========
+Simple plot
+===========
 
-A very simple pyplot where a list of numbers are plotted against their
-index. Creates a straight line due to the rate of change being 1 for
-both the X and Y axis. Use a format string (here, 'o-r') to set the
+A simple plot where a list of numbers are plotted against their index,
+resulting in a straight line. Use a format string (here, 'o-r') to set the
 markers (circles), linestyle (solid line) and color (red).
 
 .. redirect-from:: /gallery/pyplots/fig_axes_labels_simple
 .. redirect-from:: /gallery/pyplots/pyplot_formatstr
 """
+
 import matplotlib.pyplot as plt
 
 plt.plot([1, 2, 3, 4], 'o-r')

examples/pyplots/pyplot_simple.py

@@ -1,29 +1,29 @@
 """
-===========
-Pyplot Text
-===========
+==============================
+Text and mathtext using pyplot
+==============================
 
-"""
-import numpy as np
-import matplotlib.pyplot as plt
+Set the special text objects `~.pyplot.title`, `~.pyplot.xlabel`, and
+`~.pyplot.ylabel` through the dedicated pyplot functions.  Additional text
+objects can be placed in the axes using `~.pyplot.text`.
 
-# Fixing random state for reproducibility
-np.random.seed(19680801)
+You can use TeX-like mathematical typesetting in all texts; see also
+:doc:`/tutorials/text/mathtext`.
 
-mu, sigma = 100, 15
-x = mu + sigma * np.random.randn(10000)
+.. redirect-from:: /gallery/pyplots/pyplot_mathtext
+"""
 
-# the histogram of the data
-n, bins, patches = plt.hist(x, 50, density=True, facecolor='g', alpha=0.75)
+import numpy as np
+import matplotlib.pyplot as plt
 
+t = np.arange(0.0, 2.0, 0.01)
+s = np.sin(2*np.pi*t)
 
-plt.xlabel('Smarts')
-plt.ylabel('Probability')
-plt.title('Histogram of IQ')
-plt.text(60, .025, r'$\mu=100,\ \sigma=15$')
-plt.xlim(40, 160)
-plt.ylim(0, 0.03)
-plt.grid(True)
+plt.plot(t, s)
+plt.text(0, -1, r'Hello, world!', fontsize=15)
+plt.title(r'$\mathcal{A}\sin(\omega t)$', fontsize=20)
+plt.xlabel('Time [s]')
+plt.ylabel('Voltage [mV]')
 plt.show()
 
 #############################################################################

examples/pyplots/pyplot_text.py

@@ -1,10 +1,11 @@
 """
-============
-Pyplot Three
-============
+===========================
+Multiple lines using pyplot
+===========================
 
-Plot three line plots in a single call to `~matplotlib.pyplot.plot`.
+Plot three datasets with a single call to `~matplotlib.pyplot.plot`.
 """
+
 import numpy as np
 import matplotlib.pyplot as plt
 

examples/pyplots/pyplot_three.py

@@ -1,10 +1,11 @@
 """
-===================
-Pyplot Two Subplots
-===================
+=========================
+Two subplots using pyplot
+=========================
 
-Create a figure with two subplots with `.pyplot.subplot`.
+Create a figure with two subplots using `.pyplot.subplot`.
 """
+
 import numpy as np
 import matplotlib.pyplot as plt
 

examples/pyplots/pyplot_two_subplots.py

@@ -354,7 +354,7 @@
 -------
 Here is an example illustrating many of these features in context.
 
-.. figure:: ../../gallery/pyplots/images/sphx_glr_pyplot_mathtext_001.png
-   :target: ../../gallery/pyplots/pyplot_mathtext.html
+.. figure:: ../../gallery/text_labels_and_annotations/images/sphx_glr_mathtext_demo_001.png
+   :target: ../../gallery/text_labels_and_annotations/mathtext_demo.html
    :align: center
 """