meanMargin

Mean classification margin

Syntax

mar = meanMargin(B,TBLnew,Ynew)
mar = meanMargin(B,Xnew,Ynew)
mar = meanMargin(B,TBLnew,Ynew,'param1',val1,'param2',val2,...)
mar = meanMargin(B,Xnew,Ynew,'param1',val1,'param2',val2,...)

Description

mar = meanMargin(B,TBLnew,Ynew) computes average classification margins for the predictors contained in the table TBLnew given the true response Ynew. You can omit Ynew if TBLnew contains the response variable. If you trained B using sample data contained in a table, then the input data for this method must also be in a table.

mar = meanMargin(B,Xnew,Ynew) computes average classification margins for the predictors contained in the matrix Xnew given true response Ynew. If you trained B using sample data contained in a matrix, then the input data for this method must also be in a matrix.

Ynew can be a numeric vector, character matrix, string array, cell array of character vectors, categorical vector, or logical vector. meanMargin averages the margins over all observations (rows) in TBLnew or Xnew for each tree. mar is a matrix of size 1-by-NTrees, where NTrees is the number of trees in the ensemble B. This method is available for classification ensembles only.

mar = meanMargin(B,TBLnew,Ynew,'param1',val1,'param2',val2,...) or mar = meanMargin(B,Xnew,Ynew,'param1',val1,'param2',val2,...) specifies optional parameter name-value pairs:

'Mode'How meanMargin computes errors. If set to 'cumulative' (default), is a vector of length NTrees where the first element gives mean margin from trees(1), second column gives mean margins from trees(1:2) etc., up to trees(1:NTrees). If set to 'individual', mar is a vector of length NTrees, where each element is a mean margin from each tree in the ensemble. If set to 'ensemble', mar is a scalar showing the cumulative mean margin for the entire ensemble.
'Trees'Vector of indices indicating what trees to include in this calculation. By default, this argument is set to 'all' and the method uses all trees. If 'Trees' is a numeric vector, the method returns a vector of length NTrees for 'cumulative' and 'individual' modes, where NTrees is the number of elements in the input vector, and a scalar for 'ensemble' mode. For example, in the 'cumulative' mode, the first element gives mean margin from trees(1), the second element gives mean margin from trees(1:2) etc.
'TreeWeights'Vector of tree weights. This vector must have the same length as the 'Trees' vector. meanMargin uses these weights to combine output from the specified trees by taking a weighted average instead of the simple nonweighted majority vote. You cannot use this argument in the 'individual' mode.
'UseInstanceForTree'Logical matrix of size Nobs-by-NTrees indicating which trees to use to make predictions for each observation. By default, the method uses all trees for all observations.
'Weights'Vector of observation weights to use for margin averaging. By default, the weight of each observation is set to 1. The length of this vector must be equal to the number of rows in X.

See Also