Question

我正在尝试在python中进行曲线拟合，并且遇到了一个奇怪的错误。我不确定这个错误的起源是什么。当我以1而不是0.1的步长绘制时，我有这一步。有人可以指出我为什么会收到此错误。

import numpy as np

from matplotlib import pyplot as plt

coeff = [0.6e-4, 0.48e-3, -0.29e-2, -0.164, -0.400, -0.472, -0.330, -0.057, 0.306, 0.689, 1.061, 1.406, 1.715, 1.986, 2.223, 2.432, 2.616]

Temp  = [5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300]

coeff = [0, 0, 0, -0.164, -0.400, -0.472, -0.330, -0.057, 0.306, 0.689, 1.061, 1.406, 1.715, 1.986, 2.223, 2.432, 2.616]

Temp  = [5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300]


legends = np.polyfit(Temp,coeff,4)[::-1]

T = np.arange(4,300,1)
y = [sum([float(a*x**y) for y,a in enumerate(legends)]) for x in T]
T_ = np.arange(4,300,0.1)
y_ = [sum([a*x**y for y,a in enumerate(legends)]) for x in T_]

plt.figure()
plt.plot(Temp,coeff,"ko")
plt.plot(T,y,"ro")
plt.plot(T_,y_,"go")

plt.show()

Answer 1

当我运行你的代码时，我收到了消息

Traceback (most recent call last):
   File "test.py", line 26, in <module>
       plt.plot(T,y,"ro")
   File "/astromake/opt/casa/stable/lib/python2.7/site-packages/matplotlib/pyplot.py", line 2458, in plot
       ret = ax.plot(*args, **kwargs)
   File "/astromake/opt/casa/stable/lib/python2.7/site-packages/matplotlib/axes.py", line 3848, in plot
       for line in self._get_lines(*args, **kwargs):
   File "/astromake/opt/casa/stable/lib/python2.7/site-packages/matplotlib/axes.py", line 323, in _grab_next_args
       for seg in self._plot_args(remaining, kwargs):
   File "/astromake/opt/casa/stable/lib/python2.7/site-packages/matplotlib/axes.py", line 300, in _plot_args
       x, y = self._xy_from_xy(x, y)
   File "/astromake/opt/casa/stable/lib/python2.7/site-packages/matplotlib/axes.py", line 240, in _xy_from_xy
       raise ValueError("x and y must have same first dimension")
ValueError: x and y must have same first dimension

这告诉您代码在第26行失败，原因是T和y的类型不同。这是真的：T是np.array，而y是列表。您可以通过在y：

上调用np.asarray（）来解决此问题

y = np.asarray([sum([float(a*x**y) for y,a in enumerate(legends)]) for x in T])

和

y_ = np.asarray([sum([a*x**y for y,a in enumerate(legends)]) for x in T_])

顺便说一下，我做了一个快速的谷歌搜索，发现了this问题，基本上也给出了问题的答案。

Answer 2

问题是，在分配y和enumerate()时，您正在重复y变量名称（在y_中），以便在您进行绘图时，y不再与x形状相同。

尝试：

T = np.arange(4,300,1)
y = [sum([float(a*x**m) for m,a in enumerate(legends)]) for x in T] # note the change from y -> m

T_ = np.arange(4,300,0.1)
y_ = [sum([a*x**n for n,a in enumerate(legends)]) for x in T_] # note the change from y -> n

绘制不同步长的Python错误

2 个答案: