This example shows how to view a classification or regression tree. There are two ways to view a tree:view(tree)
returns a text description andview(tree,'mode','graph')
returns a graphic description of the tree.
Create and view a classification tree.
loadfisheriris% load the sample datactree = fitctree(meas,species);% create classification treeview(ctree)% text description
Decision tree for classification 1 if x3<2.45 then node 2 elseif x3>=2.45 then node 3 else setosa 2 class = setosa 3 if x4<1.75 then node 4 elseif x4>=1.75 then node 5 else versicolor 4 if x3<4.95 then node 6 elseif x3>=4.95 then node 7 else versicolor 5 class = virginica 6 if x4<1.65 then node 8 elseif x4>=1.65 then node 9 else versicolor 7 class = virginica 8 class = versicolor 9 class = virginica
view(ctree,'mode','graph')% graphic description
Now, create and view a regression tree.
loadcarsmall% load the sample data, contains Horsepower, Weight, MPGX = [Horsepower Weight]; rtree = fitrtree(X,MPG,'MinParent',30);% create classification treeview(rtree)% text description
Decision tree for regression 1 if x2<3085.5 then node 2 elseif x2>=3085.5 then node 3 else 23.7181 2 if x1<89 then node 4 elseif x1>=89 then node 5 else 28.7931 3 if x1<115 then node 6 elseif x1>=115 then node 7 else 15.5417 4 if x2<2162 then node 8 elseif x2>=2162 then node 9 else 30.9375 5 fit = 24.0882 6 fit = 19.625 7 fit = 14.375 8 fit = 33.3056 9 fit = 29
view(rtree,'mode','graph')% graphic description
fitctree
|fitrtree
|view (CompactClassificationTree)
|view (CompactRegressionTree)