Python在样条插值中保留点

Question

我编写了一个执行样条插值的代码:

x1 = [ 0., 13.99576991, 27.99153981, 41.98730972, 55.98307963, 69.97884954, 83.97461944, 97.97038935, 111.9661593, 125.9619292, 139.9576991, 153.953469 ]
y1 = [ 1., 0.88675318, 0.67899118, 0.50012243, 0.35737022, 0.27081293, 0.18486778, 0.11043095, 0.08582272, 0.04946131, 0.04285015, 0.02901567]

x = np.array(x1) 
y = np.array(y1)

# Interpolate the data using a cubic spline to "new_length" samples
new_length = 50
new_x = np.linspace(x.min(), x.max(), new_length)
new_y = sp.interpolate.interp1d(x, y, kind='cubic')(new_x)

但是在生成的新数据集中 new_x,new_y原始点被消除,只保留第一个和最后一个值.我想保留原点.

Answer 1

linspace是的,x除了传递给它的那些(x.min()和x.max())之外,不会生成任何值.

我没有一个很好的答案,但这是一种方法:

# Interpolate the data using a cubic spline to "new_length" samples
new_length = 50
interpolated_x = np.linspace(x.min(), x.max(), new_length - len(x) + 2)
new_x = np.sort(np.append(interpolated_x, x[1:-1]))  # include the original points
new_y = sp.interpolate.interp1d(x, y, kind='cubic')(new_x)

此代码使用:

• np.linspace 根据需要创建尽可能多的额外点
• np.append 将加点数组与原始点相结合 x
• np.sort 将组合数组按顺序排列