update matplotlib tutorials

Author: Mofan

matplotlibTUT/plt10_scatter.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 10 - scatter
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial reference:
+http://www.scipy-lectures.org/intro/matplotlib/matplotlib.html
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+n = 1024    # data size
+X = np.random.normal(0, 1, n)
+Y = np.random.normal(0, 1, n)
+T = np.arctan2(Y, X)    # for color later on
+
+plt.scatter(X, Y, s=75, c=T, alpha=.5)
+
+plt.xlim(-1.5, 1.5)
+plt.xticks(())  # ignore xticks
+plt.ylim(-1.5, 1.5)
+plt.yticks(())  # ignore yticks
+
+plt.show()

matplotlibTUT/plt11_bar.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 11 - bar
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial reference:
+http://www.scipy-lectures.org/intro/matplotlib/matplotlib.html
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+n = 12
+X = np.arange(n)
+Y1 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)
+Y2 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)
+
+plt.bar(X, +Y1, facecolor='#9999ff', edgecolor='white')
+plt.bar(X, -Y2, facecolor='#ff9999', edgecolor='white')
+
+for x, y in zip(X, Y1):
+    # ha: horizontal alignment
+    # va: vertical alignment
+    plt.text(x + 0.4, y + 0.05, '%.2f' % y, ha='center', va='bottom')
+
+for x, y in zip(X, Y2):
+    # ha: horizontal alignment
+    # va: vertical alignment
+    plt.text(x + 0.4, -y - 0.05, '%.2f' % y, ha='center', va='top')
+
+plt.xlim(-.5, n)
+plt.xticks(())
+plt.ylim(-1.25, 1.25)
+plt.yticks(())
+
+plt.show()

matplotlibTUT/plt12_contours.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 12 - contours
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial reference:
+http://www.scipy-lectures.org/intro/matplotlib/matplotlib.html
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+def f(x,y):
+    # the height function
+    return (1 - x / 2 + x**5 + y**3) * np.exp(-x**2 -y**2)
+
+n = 256
+x = np.linspace(-3, 3, n)
+y = np.linspace(-3, 3, n)
+X,Y = np.meshgrid(x, y)
+
+# use plt.contourf to filling contours
+# X, Y and value for (X,Y) point
+plt.contourf(X, Y, f(X, Y), 8, alpha=.75, cmap=plt.cm.hot)
+
+# use plt.contour to add contour lines
+C = plt.contour(X, Y, f(X, Y), 8, colors='black', linewidth=.5)
+# adding label
+plt.clabel(C, inline=True, fontsize=10)
+
+plt.xticks(())
+plt.yticks(())
+plt.show()
+

matplotlibTUT/plt13_image.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 13 - image
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+# image data
+a = np.array([0.313660827978, 0.365348418405, 0.423733120134,
+              0.365348418405, 0.439599930621, 0.525083754405,
+              0.423733120134, 0.525083754405, 0.651536351379]).reshape(3,3)
+
+"""
+for the value of "interpolation", check this:
+http://matplotlib.org/examples/images_contours_and_fields/interpolation_methods.html
+for the value of "origin"= ['upper', 'lower'], check this:
+http://matplotlib.org/examples/pylab_examples/image_origin.html
+"""
+plt.imshow(a, interpolation='nearest', cmap='bone', origin='lower')
+plt.colorbar(shrink=.92)
+
+plt.xticks(())
+plt.yticks(())
+plt.show()
+

matplotlibTUT/plt14_3d.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 14 - 3d
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial page:
+http://www.python-course.eu/matplotlib_multiple_figures.php
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+from mpl_toolkits.mplot3d import Axes3D
+
+fig = plt.figure()
+ax = Axes3D(fig)
+# X, Y value
+X = np.arange(-4, 4, 0.25)
+Y = np.arange(-4, 4, 0.25)
+X, Y = np.meshgrid(X, Y)
+R = np.sqrt(X ** 2 + Y ** 2)
+# height value
+Z = np.sin(R)
+
+ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=plt.cm.hot)
+"""
+============= ================================================
+        Argument      Description
+        ============= ================================================
+        *X*, *Y*, *Z* Data values as 2D arrays
+        *rstride*     Array row stride (step size), defaults to 10
+        *cstride*     Array column stride (step size), defaults to 10
+        *color*       Color of the surface patches
+        *cmap*        A colormap for the surface patches.
+        *facecolors*  Face colors for the individual patches
+        *norm*        An instance of Normalize to map values to colors
+        *vmin*        Minimum value to map
+        *vmax*        Maximum value to map
+        *shade*       Whether to shade the facecolors
+        ============= ================================================
+"""
+
+# I think this is different from plt12_contours
+ax.contourf(X, Y, Z, zdir='z', offset=-2, cmap=plt.cm.hot)
+"""
+==========  ================================================
+        Argument    Description
+        ==========  ================================================
+        *X*, *Y*,   Data values as numpy.arrays
+        *Z*
+        *zdir*      The direction to use: x, y or z (default)
+        *offset*    If specified plot a projection of the filled contour
+                    on this position in plane normal to zdir
+        ==========  ================================================
+"""
+
+ax.set_zlim(-2, 2)
+
+plt.show()
+

matplotlibTUT/plt15_subplot.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 15 - subplot
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial page:
+http://www.scipy-lectures.org/intro/matplotlib/matplotlib.html
+"""
+
+import matplotlib.pyplot as plt
+
+# example 1:
+###############################
+plt.figure(figsize=(6, 4))
+# plt.subplot(n_rows, n_cols, plot_num)
+plt.subplot(2, 2, 1)
+plt.plot([0, 1], [0, 1])
+
+plt.subplot(222)
+plt.plot([0, 1], [0, 2])
+
+plt.subplot(223)
+plt.plot([0, 1], [0, 3])
+
+plt.subplot(224)
+plt.plot([0, 1], [0, 4])
+
+plt.tight_layout()
+
+# example 2:
+###############################
+plt.figure(figsize=(6, 4))
+# plt.subplot(n_rows, n_cols, plot_num)
+plt.subplot(2, 1, 1)
+# figure splits into 2 rows, 1 col, plot to the 1st sub-fig
+plt.plot([0, 1], [0, 1])
+
+plt.subplot(234)
+# figure splits into 2 rows, 3 col, plot to the 4th sub-fig
+plt.plot([0, 1], [0, 2])
+
+plt.subplot(235)
+# figure splits into 2 rows, 3 col, plot to the 5th sub-fig
+plt.plot([0, 1], [0, 3])
+
+plt.subplot(236)
+# figure splits into 2 rows, 3 col, plot to the 6th sub-fig
+plt.plot([0, 1], [0, 4])
+
+
+plt.tight_layout()
+plt.show()

matplotlibTUT/plt16_grid_subplot.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 16 - grid
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial page:
+http://matplotlib.org/users/gridspec.html
+"""
+
+import matplotlib.pyplot as plt
+import matplotlib.gridspec as gridspec
+
+# method 1: subplot2grid
+##########################
+plt.figure()
+ax1 = plt.subplot2grid((3, 3), (0, 0), colspan=3)  # stands for axes
+ax1.plot([1, 2], [1, 2])
+ax1.set_title('ax1_title')
+ax2 = plt.subplot2grid((3, 3), (1, 0), colspan=2)
+ax3 = plt.subplot2grid((3, 3), (1, 2), rowspan=2)
+ax4 = plt.subplot2grid((3, 3), (2, 0))
+ax4.scatter([1, 2], [2, 2])
+ax4.set_xlabel('ax4_x')
+ax4.set_ylabel('ax4_y')
+ax5 = plt.subplot2grid((3, 3), (2, 1))
+
+# method 2: gridspec
+#########################
+plt.figure()
+gs = gridspec.GridSpec(3, 3)
+# use index from 0
+ax6 = plt.subplot(gs[0, :])
+ax7 = plt.subplot(gs[1, :2])
+ax8 = plt.subplot(gs[1:, 2])
+ax9 = plt.subplot(gs[-1, 0])
+ax10 = plt.subplot(gs[-1, -2])
+
+# method 3: easy to define structure
+####################################
+f, ((ax11, ax12), (ax13, ax14)) = plt.subplots(2, 2, sharex=True, sharey=True)
+ax11.scatter([1,2], [1,2])
+
+plt.tight_layout()
+plt.show()

matplotlibTUT/plt17_plot_in_plot.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 17 - plot in plot
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial page:
+http://www.python-course.eu/matplotlib_multiple_figures.php
+"""
+
+import matplotlib.pyplot as plt
+import matplotlib.gridspec as gridspec
+
+fig = plt.figure()
+x = [1, 2, 3, 4, 5, 6, 7]
+y = [1, 3, 4, 2, 5, 8, 6]
+
+# below are all percentage
+left, bottom, width, height = 0.1, 0.1, 0.8, 0.8
+ax1 = fig.add_axes([left, bottom, width, height])  # main axes
+ax1.plot(x, y, 'r')
+ax1.set_xlabel('x')
+ax1.set_ylabel('y')
+ax1.set_title('title')
+
+ax2 = fig.add_axes([0.2, 0.6, 0.25, 0.25])  # inside axes
+ax2.plot(y, x, 'b')
+ax2.set_xlabel('x')
+ax2.set_ylabel('y')
+ax2.set_title('title inside 1')
+
+
+# different method to add axes
+####################################
+plt.axes([0.6, 0.2, 0.25, 0.25])
+plt.plot(y[::-1], x, 'g')
+plt.xlabel('x')
+plt.ylabel('y')
+plt.title('title inside 2')
+
+plt.show()

matplotlibTUT/plt18_secondary_yaxis.py

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+# View more python tutorials on my Youtube and Youku channel!!!
+
+# Youtube video tutorial: https://www.youtube.com/channel/UCdyjiB5H8Pu7aDTNVXTTpcg
+# Youku video tutorial: http://i.youku.com/pythontutorial
+
+# 18 - secondary y axis
+"""
+Please note, this script is for python3+.
+If you are using python2+, please modify it accordingly.
+Tutorial page:
+http://www.python-course.eu/matplotlib_multiple_figures.php
+"""
+
+import matplotlib.pyplot as plt
+import numpy as np
+
+x = np.arange(0, 10, 0.1)
+y1 = 0.05 * x**2
+y2 = -1 *y1
+
+fig, ax1 = plt.subplots()
+
+ax2 = ax1.twinx()    # mirror the ax1
+ax1.plot(x, y1, 'g-')
+ax2.plot(x, y2, 'b-')
+
+ax1.set_xlabel('X data')
+ax1.set_ylabel('Y1 data', color='g')
+ax2.set_ylabel('Y2 data', color='b')
+
+plt.show()