Pros and cons of multivariate interpolation techniques for scattered data?












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I have a numerical simulation $f$ that takes 6 input parameters $mathbf x = x_1, x_2, ldots x_6$. I have randomly selected $25,000$ random combinations of these inputs and calculated $f(mathbf x)$. The output of the simulation is about 25 numbers $mathbf y = y_1, y_2, ldots y_{25}$ (although for the sake of simplicity we could pretend I am only computing $y_1$).



I am now trying to interpolate this function 6-dimensional function. I hold out a model, train on the remaining models, and test on the held-out model.



I have tried various schemes:




  • Linear interpolation (scipy.interpolate.griddata)


  • Artificial neural network (sklearn.neural_network.MLPRegressor)


  • Kriging / Gaussian Process Regression (sklearn.gaussian_process.gaussianProcessRegressor)


  • Polynomial ridge regression (e.g., polynomial features)


  • Distance-weighted nearest neighbors (K Nearest Neighbors)



To my surprise, linear interpolation has outperformed the rest. (To be clear, I have tried various data preprocessing steps to ensure the data are normalized, etc., as well as several hours changing the parameters of each method.)



Is this what I should have expected? Is there another technique that may work better?



I would like to note that I have apparently failed to find a method that can do cubic interpolation with high dimensional input, which I would imagine to be a promising route. (SciPy at least is limited to 2D functions.)










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    $begingroup$


    I have a numerical simulation $f$ that takes 6 input parameters $mathbf x = x_1, x_2, ldots x_6$. I have randomly selected $25,000$ random combinations of these inputs and calculated $f(mathbf x)$. The output of the simulation is about 25 numbers $mathbf y = y_1, y_2, ldots y_{25}$ (although for the sake of simplicity we could pretend I am only computing $y_1$).



    I am now trying to interpolate this function 6-dimensional function. I hold out a model, train on the remaining models, and test on the held-out model.



    I have tried various schemes:




    • Linear interpolation (scipy.interpolate.griddata)


    • Artificial neural network (sklearn.neural_network.MLPRegressor)


    • Kriging / Gaussian Process Regression (sklearn.gaussian_process.gaussianProcessRegressor)


    • Polynomial ridge regression (e.g., polynomial features)


    • Distance-weighted nearest neighbors (K Nearest Neighbors)



    To my surprise, linear interpolation has outperformed the rest. (To be clear, I have tried various data preprocessing steps to ensure the data are normalized, etc., as well as several hours changing the parameters of each method.)



    Is this what I should have expected? Is there another technique that may work better?



    I would like to note that I have apparently failed to find a method that can do cubic interpolation with high dimensional input, which I would imagine to be a promising route. (SciPy at least is limited to 2D functions.)










    share|cite|improve this question









    $endgroup$















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      0





      $begingroup$


      I have a numerical simulation $f$ that takes 6 input parameters $mathbf x = x_1, x_2, ldots x_6$. I have randomly selected $25,000$ random combinations of these inputs and calculated $f(mathbf x)$. The output of the simulation is about 25 numbers $mathbf y = y_1, y_2, ldots y_{25}$ (although for the sake of simplicity we could pretend I am only computing $y_1$).



      I am now trying to interpolate this function 6-dimensional function. I hold out a model, train on the remaining models, and test on the held-out model.



      I have tried various schemes:




      • Linear interpolation (scipy.interpolate.griddata)


      • Artificial neural network (sklearn.neural_network.MLPRegressor)


      • Kriging / Gaussian Process Regression (sklearn.gaussian_process.gaussianProcessRegressor)


      • Polynomial ridge regression (e.g., polynomial features)


      • Distance-weighted nearest neighbors (K Nearest Neighbors)



      To my surprise, linear interpolation has outperformed the rest. (To be clear, I have tried various data preprocessing steps to ensure the data are normalized, etc., as well as several hours changing the parameters of each method.)



      Is this what I should have expected? Is there another technique that may work better?



      I would like to note that I have apparently failed to find a method that can do cubic interpolation with high dimensional input, which I would imagine to be a promising route. (SciPy at least is limited to 2D functions.)










      share|cite|improve this question









      $endgroup$




      I have a numerical simulation $f$ that takes 6 input parameters $mathbf x = x_1, x_2, ldots x_6$. I have randomly selected $25,000$ random combinations of these inputs and calculated $f(mathbf x)$. The output of the simulation is about 25 numbers $mathbf y = y_1, y_2, ldots y_{25}$ (although for the sake of simplicity we could pretend I am only computing $y_1$).



      I am now trying to interpolate this function 6-dimensional function. I hold out a model, train on the remaining models, and test on the held-out model.



      I have tried various schemes:




      • Linear interpolation (scipy.interpolate.griddata)


      • Artificial neural network (sklearn.neural_network.MLPRegressor)


      • Kriging / Gaussian Process Regression (sklearn.gaussian_process.gaussianProcessRegressor)


      • Polynomial ridge regression (e.g., polynomial features)


      • Distance-weighted nearest neighbors (K Nearest Neighbors)



      To my surprise, linear interpolation has outperformed the rest. (To be clear, I have tried various data preprocessing steps to ensure the data are normalized, etc., as well as several hours changing the parameters of each method.)



      Is this what I should have expected? Is there another technique that may work better?



      I would like to note that I have apparently failed to find a method that can do cubic interpolation with high dimensional input, which I would imagine to be a promising route. (SciPy at least is limited to 2D functions.)







      numerical-methods regression interpolation simulation






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      asked Dec 16 '18 at 12:14









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