样条插值与Python(Spline Interpolation with Python)

2019-06-26 20:44发布

我写了下面的代码来执行样条插补:

import numpy as np
import scipy as sp

x1 = [1., 0.88,  0.67,  0.50,  0.35,  0.27, 0.18,  0.11,  0.08,  0.04,  0.04,  0.02]
y1 = [0., 13.99, 27.99, 41.98, 55.98, 69.97, 83.97, 97.97, 111.96, 125.96, 139.95, 153.95]

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

new_length = 25
new_x = np.linspace(x.min(), x.max(), new_length)
new_y = sp.interpolate.interp1d(x, y, kind='cubic')(new_x)

但我得到:

ValueError: A value in x_new is below the interpolation range.

interpolate.py

任何帮助,将不胜感激。

Answer 1:

从上scipy.interpolate.interp1d SciPy的文件 :

scipy.interpolate.interp1d(X,Y,种类= '线性',轴线= -1,复制=真,bounds_error =真,fill_value = np.nan)

X:array_like。 的A 1-d阵列单调递增的实数值。

...

问题是,x值不单调递增 。 事实上,他们是单调递减。 让我知道这是否正常工作,如果它仍然是计算你正在寻找:

import numpy as np
import scipy as sp
from scipy.interpolate import interp1d

x1 = sorted([1., 0.88, 0.67, 0.50, 0.35, 0.27, 0.18, 0.11, 0.08, 0.04, 0.04, 0.02])
y1 = [0., 13.99, 27.99, 41.98, 55.98, 69.97, 83.97, 97.97, 111.96, 125.96, 139.95, 153.95]

new_length = 25
new_x = np.linspace(x.min(), x.max(), new_length)
new_y = sp.interpolate.interp1d(x, y, kind='cubic')(new_x)


Answer 2:

您可以通过以下方式得到这样的:

import numpy as np
import scipy as sp
from scipy.interpolate import interp1d

x1 = [1., 0.88,  0.67,  0.50,  0.35,  0.27, 0.18,  0.11,  0.08,  0.04,  0.04,  0.02]
y1 = [0., 13.99, 27.99, 41.98, 55.98, 69.97, 83.97, 97.97, 111.96, 125.96, 139.95, 153.95]

# Combine lists into list of tuples
points = zip(x1, y1)

# Sort list of tuples by x-value
points = sorted(points, key=lambda point: point[0])

# Split list of tuples into two list of x values any y values
x1, y1 = zip(*points)

new_length = 25
new_x = np.linspace(min(x1), max(x1), new_length)
new_y = sp.interpolate.interp1d(x1, y1, kind='cubic')(new_x)


文章来源: Spline Interpolation with Python