Figure 12: A two dimensional contour plot of with a quadratic local model
All of the examples so far have been on one dimensional data sets, but all of the methods presented so far generalize easily to multivariate inputs and outputs. We can see the fits of two dimensional data with contour plots. a2.mbl is a data file containing 100 data points with two input dimensions and one output dimension. The data was generated with the following equation:
File -> Open -> a2.mbl Edit -> Metacode -> Localness 4: Very local Regression Q: Quadratic Model -> Graph -> Dimensions 2 Graph
The graph is shown in fig. 12. The contours show the approximated function and have the expected shape of smooth peaks mixed between smooth valleys. The data points are also shown. It is no longer possible, however, to evaluate how well the function is approximated visually. The distribution of the data points in input space can be seen, but the height, or output value, of each data point is not represented in the plot.