使用 Python 的样条插值

Question

我编写了以下代码来执行样条插值：

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.

在interpolate.py

任何帮助将不胜感激。

Answer 1

来自scipy.interpolate.interp1d上的scipy文档：

scipy.interpolate.interp1d（x， y， kind='linear'， axis=-1， copy=True， bounds_error=True， fill_value=np.nan）

x ： array_like。单调递增实数值的一维数组。

。

问题是 x 值不是单调递增的。事实上，它们正在单调地减少。让我知道这是否有效，以及它是否仍然是您正在寻找的计算。

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获取此内容：

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)

Answer 3

我刚刚收到上述错误并通过删除 X 和 Y 数组中的重复值来修复它。

x = np.sort(np.array([0, .2, .2, .4, .6, .9]))
y = np.sort(np.sort(np.array([0, .1, .06, .11, .25, .55]))

⬇ 将 0.2 更改为 0.3 或任何数字。

x = np.sort(np.array([0, .2, .3, .4, .6, .9]))
y = np.sort(np.sort(np.array([0, .1, .06, .11, .25, .55]))