Basic Examples

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Loess is useful when data is noisy but has an underlying trend:

data=Table[{i,Sin[i]+RandomReal[0.3]},{i,0,2π,0.05}];​​ListPlot[data]
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Find an estimated value for the data at x=2 using the nearest 12 data points:

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Loess
[data,12,2]
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1.05451
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Find an estimated value for the data at x=2 using the nearest 10% of the data:

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Loess
[data,Scaled[0.10],2]
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1.04627
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ListPlotTablex,
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Loess
[data,40,x],{x,0,2π,0.2}
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Scope

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Loess can handle higher dimensional data:

data=Flatten[Table[{i,j,Sin[i+Sin[j]]+RandomReal[0.3]},{i,0,2π,0.1},{j,0,2π,0.1}],{1,2}];​​ListPlot3D[data]
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Loess
[data,30,{4,4}]
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0.0537497
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ListPlot3DFlattenTablex,y,
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Loess
[data,20,{x,y}],{x,0,6,0.2},{y,0,6,0.2},{1,2}
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Options

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By default Loess fits straight lines to subsets of data, but you can increase the interpolation order to capture different detail:

data=Table[{i,Sin[i]+RandomReal[0.3]},{i,0,2π,0.2}];​​ListPlot[data]
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Lowess fitting involves weighting the local data. Typically points further from the estimated point are given less weight:

Possible Issues

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If you intend to use Loess to predict many values from the same data, then it is more efficient to find all values in a single request:

This method:

Is faster than this method: