Difference between individual and cumulative oobMargin of TreeBagger

K
K
2011 6 16
2 个回答
回答已采纳
5 次查看（30 天）

0 个投票

Why aren't the following two plots the same?
b = TreeBagger(500,X,Y,'oobpred','on');
mc = oobMargin(b,'mode','cumulative');
mi = oobMargin(b,'mode','individual');
figure; plot(mc.')
figure; plot(bsxfun(@rdivide,cumsum(mi.'),(1:500).'))

请先登录，再回答此问题。

 采纳的回答

Ilya
Ilya 2011-6-17

0 个投票

When you ask for an OOB margin from one tree, you get zero if this observation was in bag for this tree. The margin is undefined in this case, and TreeBagger returns 0 by default. The cumulative calculation averages over trees for which this observation was out of bag only. Check this out:
>> load fisheriris
>> b = TreeBagger(10,meas,species,'oobpred','on');
>> mi = oobMargin(b,'mode','individual');
>> mi(1,:)
ans = 1 0 0 0 1 0 1 1 0 0
>> b.OOBIndices(1,:)
ans = 1 0 0 0 1 0 1 1 0 0
>> mc = oobMargin(b,'mode','cumulative');
>> mc(1,:)
ans = 1 1 1 1 1 1 1 1 1 1

更多回答（1 个）

K
K 2011-6-21

0 个投票

Code using the individual mode that produces the same plot as the cumulative mode is the following.
load ionosphere
b = TreeBagger(500,X,Y,'oobpred','on');
mc = oobMargin(b,'mode','cumulative');
mi = oobMargin(b,'mode','individual');
figure; plot(mc.')
% figure; plot(bsxfun(@rdivide,cumsum(mi.'),(1:500).'))
cumavg = zeros(size(mc));
cumavg(:,1) = mi(:,1);
for ii = 1:size(mc,1)
for jj = 2:size(mc,2)
if sum(b.OOBIndices(ii,1:jj)) == 0
cumavg(ii,jj) = mi(ii,1);
else
micurrent = mi(ii,1:jj);
cumavg(ii,jj) = mean(micurrent(b.OOBIndices(ii,1:jj)));
end
end
end
figure; plot(cumavg.')

类别

在 帮助中心 和 File Exchange 中查找有关 Classification Ensembles 的更多信息

产品

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by