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<p>我试图生成三个图,每个图使用相同的输入。
当我运行我的代码时,我为每个x输入生成一个绘图,而不是由所有数据点组成的三个绘图</p>
<p>请参见下面的代码:</p>
<pre><code>xlist = np.linspace(0, 2.5)
for name, f, df in zip(func_names, funcs, diff_funcs):
for x in xlist:
plt.plot(diff(f, x, h=0.01), 'bs', forwdiff(f, x, h=0.01), 'g^')
plt.title(name)
plt.xlabel('x')
plt.ylabel('f(x)')
bluesq = plt.Line2D([], [], color='blue', marker='s',
markersize=15, label='Centered Difference')
greentr = plt.Line2D([], [], color='green', marker='^',
markersize=15, label='Forward Difference')
l1 = plt.legend(handles = [bluesq], loc=1)
l2 = plt.legend(handles = [greentr], loc=4)
plt.gca().add_artist(l1)
plt.gca().add_artist(l2)
plt.show()
</code></pre>
<p>完整代码:</p>
<pre><code>import numpy as np
import matplotlib.pyplot as plt
print("---Forward Diff---")
def forwdiff(f, x, h=1e-5):
"""
Returns the forward derivative of a function f
"""
return 1 / (h) * (f(x + h) - f(x))
from math import exp, cos, sin, pi, log
f1 = lambda x: exp(-2 * x ** 2)
df1 = lambda x: -4 * x * exp(-2 * x ** 2)
f2 = lambda x: cos(x)
df2 = lambda x: -sin(x)
f3 = lambda x: sin(x)
df3 = lambda x: cos(x)
funcs = [f1, f2, f3]
diff_funcs = [df1, df2, df3]
func_names = ['exp(-2x^2)', 'cos(x)', 'sin(x)']
values = [2, 0.6, 0.6]
print '%10s %8s %8s %8s' % ('function', 'exact', 'approx', 'error')
for name, f, df, x in zip(func_names, funcs, diff_funcs, values):
exact = df(x)
approx = forwdiff(f, x, h=0.01)
error = abs(exact - approx)
print '%10s %.6f %.6f %.6f' % (name, exact, approx, error)
def test_forwdiff():
success = 6 - forwdiff(lambda x: x**2, 3, h=0.01) < 0.00000000001
msg = "test_forwdiff failed"
assert success, msg
print("---Centered Diff---")
def diff(f, x, h=1e-5):
"""
Returns the derivative of a function f
"""
return 1 / (2 * h) * (f(x + h) - f(x - h))
from math import exp, cos, sin, pi, log
f1 = lambda x: exp(-2 * x ** 2)
df1 = lambda x: -4 * x * exp(-2 * x ** 2)
f2 = lambda x: cos(x)
df2 = lambda x: -sin(x)
f3 = lambda x: sin(x)
df3 = lambda x: cos(x)
funcs = [f1, f2, f3]
diff_funcs = [df1, df2, df3]
func_names = ['exp(-2x^2)', 'cos(x)', 'sin(x)']
values = [2, 0.6, 0.6]
print '%10s %8s %8s %8s' % ('function', 'exact', 'approx', 'error')
for name, f, df, x in zip(func_names, funcs, diff_funcs, values):
exact = df(x)
approx = diff(f, x, h=0.01)
error = abs(exact - approx)
print '%10s %.6f %.6f %.6f' % (name, exact, approx, error)
def test_diff():
success = 6 - diff(lambda x: x**2, 3, h=0.01) < 0.00000000001
msg = "test_diff failed"
assert success, msg
xlist = np.linspace(0, 2.5)
for name, f, df in zip(func_names, funcs, diff_funcs):
for x in xlist:
plt.plot(diff(f, x, h=0.01), 'bs', forwdiff(f, x, h=0.01), 'g^')
plt.title(name)
plt.xlabel('x')
plt.ylabel('f(x)')
bluesq = plt.Line2D([], [], color='blue', marker='s',
markersize=15, label='Centered Difference')
greentr = plt.Line2D([], [], color='green', marker='^',
markersize=15, label='Forward Difference')
l1 = plt.legend(handles = [bluesq], loc=1)
l2 = plt.legend(handles = [greentr], loc=4)
plt.gca().add_artist(l1)
plt.gca().add_artist(l2)
plt.show()
</code></pre>
<p>所以,我发现plot()需要整个x\u list和y\u list作为参数</p>
<p>这让我想到:</p>
<pre><code> xlist = np.linspace(0, 2.5)
for name, f in zip(func_names, funcs):
ylist = [forwdiff(f, x, h=0.01) for x in xlist]
plt.plot(xlist, ylist, 'g^')
ylist = [diff(f, x, h=0.01) for x in xlist]
plt.plot(xlist, ylist, 'bs')
plt.title(name)
plt.xlabel('x')
plt.ylabel('f(x)')
bluesq = plt.Line2D([], [], color='blue', marker='s',
markersize=15, label='Centered Difference')
greentr = plt.Line2D([], [], color='green', marker='^',
markersize=15, label='Forward Difference')
l1 = plt.legend(handles = [bluesq], loc=1)
l2 = plt.legend(handles = [greentr], loc=4)
plt.gca().add_artist(l1)
plt.gca().add_artist(l2)
plt.show()
</code></pre>
<p>这正确地将所有输入绘制到一个绘图上,但我试图生成三个绘图。每个f输入一个。给定的代码调用f和df,并为每个函数生成一个绘图,但将它们绘图到同一个窗口。我该如何将这个图分成三个不同的窗口,分别显示forwdiff和diff</p>
<p>抱歉,如果这是一个愚蠢的问题,我的背景不是计算机科学/编程</p>
<p>对于exp(-2x2)、cos(x)和sin(x),我想将这些图分成forwdiff和diff的三个图</p>