Classification margins by resubstitution
margin = resubMargin(ens)
margin = resubMargin(ens,Name,Value)
A classification ensemble created with fitensemble.
Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.
Indices of weak learners in the ensemble ranging from 1 to NumTrained. resubMargin uses only these learners for calculating margin.
A numeric column-vector of length size(ens.X,1) containing the classification margins.
The classification margin is the difference between the classification score for the true class and maximal classification score for the false classes. Margin is a column vector with the same number of rows as in the matrix ens.X.
For ensembles, a classification score represents the confidence of a classification into a class. The higher the score, the higher the confidence.
Different ensemble algorithms have different definitions for their scores. Furthermore, the range of scores depends on ensemble type. For example:
AdaBoostM1 scores range from –∞ to ∞.
Bag scores range from 0 to 1.
Find the resubstitution margins for an ensemble that classifies the Fisher iris data:
load fisheriris ens = fitensemble(meas,species,'AdaBoostM2',100,'Tree'); margin = resubMargin(ens); [min(margin) mean(margin) max(margin)] ans = -0.5674 3.2486 4.6245