繪製迴歸：ValueError異常：X和Y必須具有相同的第一維

Question

當我運行我的代碼我得到一個錯誤信息：

ValueError: x and y must have same first dimension.

import numpy as np 
from matplotlib import pyplot as plt 
from sklearn.linear_model import LogisticRegression 

x1 = np.array([0,0.6,1.2,1.5,1.8,2.5,3.3,3.9,4,4.9,5.1]) 
y1 = np.array([0,0,0,0,0,0,0,0,0,0,0]) 

x2 = np.array([3.2,3.8,4.5,5.2,5.8,6.4,6.7,7.1,7.6,8.1,8.5,9]) 
y2 = np.array([1,1,1,1,1,1,1,1,1,1,1]) 

X = np.array([[0],[0.6],[1.2],[1.5],[1.8],[2.5],[3.3],[3.9],[4],[4.9],[5.1],[3.2],[3.8],[4.5],[5.2],[5.8],[6.4],[6.7],[7.1],[7.6],[8.1],[8.5],[9]]) 

Y = np.array([0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1]) 

plt.plot(x1,y1,"ro",color="blue") 
plt.plot(x2,y2,"ro",color="red") 

plt.axis([-2,10,-0.5,2]) 

plt.show() 

全部追溯

Traceback (most recent call last): 
    File "ml2.py", line 16, in <module> 
    plt.plot(x2,y2,"ro",color="red") 
    File "/usr/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 3154, in plot 
    ret = ax.plot(*args, **kwargs) 
    File "/usr/lib/python2.7/dist-packages/matplotlib/__init__.py", line 1814, in inner 
    return func(ax, *args, **kwargs) 
    File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_axes.py", line 1424, in plot 
    for line in self._get_lines(*args, **kwargs): 
    File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 386, in _grab_next_args 
    for seg in self._plot_args(remaining, kwargs): 
    File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 364, in _plot_args 
    x, y = self._xy_from_xy(x, y) 
    File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 223, in _xy_from_xy 
    raise ValueError("x and y must have same first dimension") 
ValueError: x and y must have same first dimension 

Answer 1

當調用plot時，兩個第一個參數x和y必須是相同長度的列表或數組。您的x2和y2長度不一樣。

爲了避免將來的問題，還有更好的方法來創建充滿只有一個值的數組，例如：

x2 = np.array([3.2,3.8,4.5,5.2,5.8,6.4,6.7,7.1,7.6,8.1,8.5,9]) 
y2 = np.full_like(x2, 1)