Merge pull request matplotlib#4833 from ericmjl/mep12_quiver_demo.py

mep12 on quiver_demo.py

Author: WeatherGod

examples/pylab_examples/quiver_demo.py

@@ -8,76 +8,84 @@
 The workaround is to manually expand the axes.
 
 '''
-from pylab import *
+import matplotlib.pyplot as plt
+import numpy as np
 from numpy import ma
 
-X, Y = meshgrid(arange(0, 2*pi, .2), arange(0, 2*pi, .2))
-U = cos(X)
-V = sin(Y)
+X, Y = np.meshgrid(np.arange(0, 2 * np.pi, .2), np.arange(0, 2 * np.pi, .2))
+U = np.cos(X)
+V = np.sin(Y)
 
-#1
-figure()
-Q = quiver(U, V)
-qk = quiverkey(Q, 0.5, 0.92, 2, r'$2 \frac{m}{s}$', labelpos='W',
-               fontproperties={'weight': 'bold'})
-l, r, b, t = axis()
+# 1
+plt.figure()
+Q = plt.quiver(U, V)
+qk = plt.quiverkey(Q, 0.5, 0.92, 2, r'$2 \frac{m}{s}$', labelpos='W',
+                   fontproperties={'weight': 'bold'})
+l, r, b, t = plt.axis()
 dx, dy = r - l, t - b
-axis([l - 0.05*dx, r + 0.05*dx, b - 0.05*dy, t + 0.05*dy])
+plt.axis([l - 0.05*dx, r + 0.05*dx, b - 0.05*dy, t + 0.05*dy])
 
-title('Minimal arguments, no kwargs')
+plt.title('Minimal arguments, no kwargs')
 
-#2
-figure()
-Q = quiver(X, Y, U, V, units='width')
-qk = quiverkey(Q, 0.9, 0.95, 2, r'$2 \frac{m}{s}$',
-               labelpos='E',
-               coordinates='figure',
-               fontproperties={'weight': 'bold'})
-axis([-1, 7, -1, 7])
-title('scales with plot width, not view')
+# 2
+plt.figure()
+Q = plt.quiver(X, Y, U, V, units='width')
+qk = plt.quiverkey(Q, 0.9, 0.95, 2, r'$2 \frac{m}{s}$',
+                   labelpos='E',
+                   coordinates='figure',
+                   fontproperties={'weight': 'bold'})
+plt.axis([-1, 7, -1, 7])
+plt.title('scales with plot width, not view')
 
-#3
-figure()
-Q = quiver(X[::3, ::3], Y[::3, ::3], U[::3, ::3], V[::3, ::3],
-           pivot='mid', color='r', units='inches')
-qk = quiverkey(Q, 0.5, 0.03, 1, r'$1 \frac{m}{s}$', fontproperties={'weight': 'bold'})
-plot(X[::3, ::3], Y[::3, ::3], 'k.')
-axis([-1, 7, -1, 7])
-title("pivot='mid'; every third arrow; units='inches'")
+# 3
+plt.figure()
+Q = plt.quiver(X[::3, ::3], Y[::3, ::3], U[::3, ::3], V[::3, ::3],
+               pivot='mid', color='r', units='inches')
+qk = plt.quiverkey(Q, 0.5, 0.03, 1, r'$1 \frac{m}{s}$',
+                   fontproperties={'weight': 'bold'})
+plt.plot(X[::3, ::3], Y[::3, ::3], 'k.')
+plt.axis([-1, 7, -1, 7])
+plt.title("pivot='mid'; every third arrow; units='inches'")
 
-#4
-figure()
-M = sqrt(pow(U, 2) + pow(V, 2))
-Q = quiver(X, Y, U, V, M, units='x', pivot='tip', width=0.022, scale=1/0.15)
-qk = quiverkey(Q, 0.9, 1.05, 1, r'$1 \frac{m}{s}$',
-               labelpos='E',
-               fontproperties={'weight': 'bold'})
-plot(X, Y, 'k.')
-axis([-1, 7, -1, 7])
-title("scales with x view; pivot='tip'")
+# 4
+plt.figure()
+M = np.hypot(U, V)
+Q = plt.quiver(X, Y, U, V, M,
+               units='x',
+               pivot='tip',
+               width=0.022,
+               scale=1 / 0.15)
+qk = plt.quiverkey(Q, 0.9, 1.05, 1, r'$1 \frac{m}{s}$',
+                   labelpos='E',
+                   fontproperties={'weight': 'bold'})
+plt.plot(X, Y, 'k.')
+plt.axis([-1, 7, -1, 7])
+plt.title("scales with x view; pivot='tip'")
 
-#5
-figure()
-Q = quiver(X[::3, ::3], Y[::3, ::3], U[::3, ::3], V[::3, ::3],
-           color='r', units='x',
-           linewidths=(2,), edgecolors=('k'), headaxislength=5)
-qk = quiverkey(Q, 0.5, 0.03, 1, r'$1 \frac{m}{s}$', fontproperties={'weight': 'bold'})
-axis([-1, 7, -1, 7])
-title("triangular head; scale with x view; black edges")
+# 5
+plt.figure()
+Q = plt.quiver(X[::3, ::3], Y[::3, ::3], U[::3, ::3], V[::3, ::3],
+               color='r', units='x',
+               linewidths=(2,), edgecolors=('k'), headaxislength=5)
+qk = plt.quiverkey(Q, 0.5, 0.03, 1, r'$1 \frac{m}{s}$',
+                   fontproperties={'weight': 'bold'})
+plt.axis([-1, 7, -1, 7])
+plt.title("triangular head; scale with x view; black edges")
 
-#6
-figure()
-M = zeros(U.shape, dtype='bool')
-M[U.shape[0]/3:2*U.shape[0]/3, U.shape[1]/3:2*U.shape[1]/3] = True
+# 6
+plt.figure()
+M = np.zeros(U.shape, dtype='bool')
+M[U.shape[0]/3:2*U.shape[0]/3,
+  U.shape[1]/3:2*U.shape[1]/3] = True
 U = ma.masked_array(U, mask=M)
 V = ma.masked_array(V, mask=M)
-Q = quiver(U, V)
-qk = quiverkey(Q, 0.5, 0.92, 2, r'$2 \frac{m}{s}$', labelpos='W',
-               fontproperties={'weight': 'bold'})
-l, r, b, t = axis()
+Q = plt.quiver(U, V)
+qk = plt.quiverkey(Q, 0.5, 0.92, 2, r'$2 \frac{m}{s}$', labelpos='W',
+                   fontproperties={'weight': 'bold'})
+l, r, b, t = plt.axis()
 dx, dy = r - l, t - b
-axis([l - 0.05*dx, r + 0.05*dx, b - 0.05*dy, t + 0.05*dy])
-title('Minimal arguments, no kwargs - masked values')
+plt.axis([l - 0.05 * dx, r + 0.05 * dx, b - 0.05 * dy, t + 0.05 * dy])
+plt.title('Minimal arguments, no kwargs - masked values')
 
 
-show()
+plt.show()