如何用scipy.interpolate.Rbf实现二维样域外推（类interp1d的extrapolate）

需求说明 #

• 利用scipy.interpolate.Rbf实现二维样条的范围外外推，计算Ti超出数据边界时的zi值（示例场景：计算Ti=0、Ki=4500时的zi）
• 将指定数据内容直接填入代码的data_str变量
• 未采用bisplrep与bisplev方案，因无法生成有效样条

完整代码 #

import io
import numpy as np
import pandas as pd
from scipy.interpolate import griddata, Rbf
from numpy import ma
import matplotlib.pyplot as plt

# 填入指定数据内容
data_str = """dte,4500,4550,4600,4650,4700,4750,4800,4850,4900,4950,5000,5050,5100,5150,5200,5250,5300,5350,5400,5450,5500
0.016438356,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.04109589,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.065753425,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.090410959,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.115068493,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.139726027,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.164383562,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.189041096,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.21369863,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.238356164,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.263013699,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.287671233,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.312328767,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.336986301,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.361643836,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.38630137,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.410958904,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.435616438,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.460273973,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.484931507,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.509589041,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.534246575,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.55890411,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.583561644,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.0949,0.0905,0.0862,0.082,0.0778,0.0737,0.0697,0.0657,0.0618,0.058,0.0543
0.608219178,0.1421,0.1371,0.1322,0.1273,0.1225,0.1177,0.113,0.1084,0.1038,0.0993,0.