use plt.subplots() in examples as much as possible

At the recent LBL Software Carpentry Workshop, it was pointed out that there's an inconsistency within our documentation for how to create new figures with subplots. Indeed, most examples were using the old way, something like: fig = plt.figure() ax = plt.subplot(111) # or plt.add_subplot(111) This patch changes a whole bunch of instances like the above to: fig, ax = plt.subplots() We should strive to have a minimal amount of constants in our code, especially unusual ones like `111`, which only make sense to Matlab refugees. I have left unchanged examples which were using axes keywords passed to subplot() and add_subplot(), since those end up transforming things like: figure() subplot(111, axisbg='w') to plt.subplots(subplot_kw=dict(axisbg='w')) which isn't necessarily better. I also did not touch most of the user_interfaces examples, since those did not involve using plt, but instead explicitly imported Figure, and used the OO approach on Figure instances. Also updated instaces where the old "import pylab as p" convention was used to use our standard "import matplotlib.pyplot as plt" I have also updated some, but not all uses of subplot(121) etc, but I'm a bit exhausted after doing all of these.
matplotlib · ivanov · Nov 8, 2012 · Nov 8, 2012 · Nov 10, 2012 · Nov 12, 2012
commit 5c54d8f3acac8c866ab0b75c17b7a8fb877db74d
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +1,7 @@
+2012-11-08 Replaced plt.figure and plt.subplot calls by the newer, more
+           convenient single call to plt.subplots() in the documentation
+           examples - PI
+
 2012-08-11 Fix path-closing bug in patches.Polygon, so that regardless
            of whether the path is the initial one or was subsequently
            set by set_xy(), get_xy() will return a closed path if and

diff --git a/examples/animation/animate_decay.py b/examples/animation/animate_decay.py
@@ -11,8 +11,7 @@ def data_gen():
         yield t, np.sin(2*np.pi*t) * np.exp(-t/10.)
 data_gen.t = 0
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 line, = ax.plot([], [], lw=2)
 ax.set_ylim(-1.1, 1.1)
 ax.set_xlim(0, 5)

diff --git a/examples/animation/histogram.py b/examples/animation/histogram.py
@@ -9,8 +9,7 @@
 import matplotlib.path as path
 import matplotlib.animation as animation
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 
 # histogram our data with numpy
 data = np.random.randn(1000)

diff --git a/examples/animation/old_animation/animate_decay_tk_blit.py b/examples/animation/old_animation/animate_decay_tk_blit.py
@@ -10,8 +10,7 @@ def data_gen():
     return np.sin(2*np.pi*t) * np.exp(-t/10.)
 data_gen.t = 0
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 line, = ax.plot([], [], animated=True, lw=2)
 ax.set_ylim(-1.1, 1.1)
 ax.set_xlim(0, 5)

diff --git a/examples/animation/old_animation/animation_blit_fltk.py b/examples/animation/old_animation/animation_blit_fltk.py
@@ -3,7 +3,7 @@
 import fltk
 import matplotlib
 matplotlib.use('FltkAgg')
-import pylab as p
+import matplotlib.pyplot as plt
 import numpy as npy
 import time
 
@@ -42,13 +42,13 @@ def update(self,ptr):
             sys.exit()
         return True
 
-ax = p.subplot(111)
-p.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
-p.grid() # to ensure proper background restore
+fig, ax = plt.subplots()
+plt.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
+plt.grid() # to ensure proper background restore
 # create the initial line
 x = npy.arange(0,2*npy.pi,0.01)
-line, = p.plot(x, npy.sin(x), animated=True)
-p.draw()
+line, = plt.plot(x, npy.sin(x), animated=True)
+plt.draw()
 anim=animator(ax)
 
 fltk.Fl.add_idle(anim.update)

diff --git a/examples/animation/old_animation/animation_blit_gtk.py b/examples/animation/old_animation/animation_blit_gtk.py
@@ -16,8 +16,7 @@
 import matplotlib.pyplot as plt
 
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 canvas = fig.canvas
 
 fig.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs

diff --git a/examples/animation/old_animation/animation_blit_gtk2.py b/examples/animation/old_animation/animation_blit_gtk2.py
@@ -148,9 +148,8 @@ def update_line(self, *args):
 
 
 plt.rcParams["text.usetex"] = False
-fig = plt.figure()
 
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 ax.xaxis.set_animated(True)
 ax.yaxis.set_animated(True)
 canvas = fig.canvas

diff --git a/examples/animation/old_animation/animation_blit_qt.py b/examples/animation/old_animation/animation_blit_qt.py
@@ -24,7 +24,7 @@ class BlitQT(QObject):
     def __init__(self):
         QObject.__init__(self, None, "app")
 
-        self.ax = p.subplot(111)
+        fig, self.ax = plt.subplots()
         self.canvas = self.ax.figure.canvas
         self.cnt = 0
 

diff --git a/examples/animation/old_animation/animation_blit_tk.py b/examples/animation/old_animation/animation_blit_tk.py
@@ -7,17 +7,17 @@
 matplotlib.use('TkAgg')
 
 import sys
-import pylab as p
+import matplotlib.pyplot as plt
 import numpy as npy
 import time
 
-ax = p.subplot(111)
+fig, ax = plt.subplots()
 canvas = ax.figure.canvas
 
 
 # create the initial line
 x = npy.arange(0,2*npy.pi,0.01)
-line, = p.plot(x, npy.sin(x), animated=True, lw=2)
+line, = plt.plot(x, npy.sin(x), animated=True, lw=2)
 
 def run(*args):
     background = canvas.copy_from_bbox(ax.bbox)
@@ -43,12 +43,12 @@ def run(*args):
 run.cnt = 0
 
 
-p.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
-p.grid() # to ensure proper background restore
-manager = p.get_current_fig_manager()
+plt.subplots_adjust(left=0.3, bottom=0.3) # check for flipy bugs
+plt.grid() # to ensure proper background restore
+manager = plt.get_current_fig_manager()
 manager.window.after(100, run)
 
-p.show()
+plt.show()
 
 
 
diff --git a/examples/animation/old_animation/animation_blit_wx.py b/examples/animation/old_animation/animation_blit_wx.py
@@ -24,7 +24,7 @@
     matplotlib.backends.backend_wxagg._use_accelerator(False)
 
 
-ax = p.subplot(111)
+fig, ax = plt.subplots()
 canvas = ax.figure.canvas
 
 

diff --git a/examples/animation/old_animation/draggable_legend.py b/examples/animation/old_animation/draggable_legend.py
@@ -1,13 +1,12 @@
 import matplotlib.pyplot as plt
 
-
-ax = plt.subplot(111)
+fig, ax = plt.subplots()
 ax.plot([1,2,3], label="test")
 
 l = ax.legend()
 d1 = l.draggable()
 
-xy = 1, 2        
+xy = 1, 2
 txt = ax.annotate("Test", xy, xytext=(-30, 30),
                   textcoords="offset points",
                   bbox=dict(boxstyle="round",fc=(0.2, 1, 1)),

diff --git a/examples/animation/old_animation/gtk_timeout.py b/examples/animation/old_animation/gtk_timeout.py
@@ -5,8 +5,7 @@
 
 import matplotlib.pyplot as plt
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 line, = ax.plot(np.random.rand(10))
 ax.set_ylim(0, 1)
 

diff --git a/examples/animation/old_animation/histogram_tkagg.py b/examples/animation/old_animation/histogram_tkagg.py
@@ -11,8 +11,7 @@
 import matplotlib.patches as patches
 import matplotlib.path as path
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 
 # histogram our data with numpy
 data = np.random.randn(1000)

diff --git a/examples/animation/old_animation/simple_anim_gtk.py b/examples/animation/old_animation/simple_anim_gtk.py
@@ -9,9 +9,7 @@
 
 import matplotlib.pyplot as plt
 
-fig = plt.figure()
-
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 
 def animate():
     tstart = time.time()                 # for profiling

diff --git a/examples/animation/old_animation/simple_anim_tkagg.py b/examples/animation/old_animation/simple_anim_tkagg.py
@@ -10,8 +10,7 @@
 matplotlib.use('TkAgg') # do this before importing pylab
 
 import matplotlib.pyplot as plt
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 
 def animate():
     tstart = time.time()                   # for profiling

diff --git a/examples/animation/old_animation/simple_idle_wx.py b/examples/animation/old_animation/simple_idle_wx.py
@@ -9,9 +9,7 @@
 
 import matplotlib.pyplot as plt
 
-fig = plt.figure()
-
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 t = np.arange(0, 2*np.pi, 0.1)
 line, = ax.plot(t, np.sin(t))
 dt = 0.05

diff --git a/examples/animation/old_animation/simple_timer_wx.py b/examples/animation/old_animation/simple_timer_wx.py
@@ -9,9 +9,7 @@
 
 import matplotlib.pyplot as plt
 
-fig = plt.figure()
-
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 t = np.arange(0, 2*np.pi, 0.1)
 line, = ax.plot(t, np.sin(t))
 dt = 0.05

diff --git a/examples/animation/old_animation/strip_chart_demo.py b/examples/animation/old_animation/strip_chart_demo.py
@@ -64,8 +64,7 @@ def update(self, *args):
 
 from pylab import figure, show
 
-fig = figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 scope = Scope(ax)
 gobject.idle_add(scope.update)
 

diff --git a/examples/animation/random_data.py b/examples/animation/random_data.py
@@ -2,8 +2,7 @@
 import matplotlib.pyplot as plt
 import matplotlib.animation as animation
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 line, = ax.plot(np.random.rand(10))
 ax.set_ylim(0, 1)
 

diff --git a/examples/animation/simple_anim.py b/examples/animation/simple_anim.py
@@ -5,8 +5,7 @@
 import matplotlib.pyplot as plt
 import matplotlib.animation as animation
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 
 x = np.arange(0, 2*np.pi, 0.01)        # x-array
 line, = ax.plot(x, np.sin(x))

diff --git a/examples/animation/strip_chart_demo.py b/examples/animation/strip_chart_demo.py
@@ -44,8 +44,7 @@ def emitter(p=0.03):
         else:
             yield np.random.rand(1)
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 scope = Scope(ax)
 
 # pass a generator in "emitter" to produce data for the update func

diff --git a/examples/api/README.txt b/examples/api/README.txt
@@ -29,8 +29,7 @@ A simple example of the recommended style is::
     import numpy as np
     import matplotlib.pyplot as plt
 
-    fig = plt.figure()
-    ax = fig.add_subplot(111) # or add_axes
+    fig, ax = plt.subplots()
     ax.plot(np.random.rand(10))
     ax.set_xlabel('some x data')
     ax.set_ylabel('some y data')

diff --git a/examples/api/agg_oo.py b/examples/api/agg_oo.py
@@ -6,12 +6,10 @@
 from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
 from matplotlib.figure import Figure
 
-fig = Figure()
-canvas = FigureCanvas(fig)
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 ax.plot([1,2,3])
 ax.set_title('hi mom')
 ax.grid(True)
 ax.set_xlabel('time')
 ax.set_ylabel('volts')
-canvas.print_figure('test')
+fig.canvas.print_figure('test')
diff --git a/examples/api/barchart_demo.py b/examples/api/barchart_demo.py
@@ -11,8 +11,7 @@
 ind = np.arange(N)  # the x locations for the groups
 width = 0.35       # the width of the bars
 
-fig = plt.figure()
-ax = fig.add_subplot(111)
+fig, ax = plt.subplots()
 rects1 = ax.bar(ind, menMeans, width, color='r', yerr=menStd)
 
 womenMeans = (25, 32, 34, 20, 25)