})
})
})
Describe("#Decide", func() {
var input []string
Describe("when the node value is a boolean", func() {
It("returns the node value", func() {
gomock.InOrder(
mockBinaryTree.EXPECT().Value().Return(true),
mockBinaryTree.EXPECT().Value().Return(false),
)
Expect(myTree.Decide(input)).To(Equal(true))
Expect(myTree.Decide(input)).To(Equal(false))
})
})
Describe("when the node value is a string label", func() {
var (
mockDecisionTree *mdt.MockInterface
)
BeforeEach(func() {
mockDecisionTree = mdt.NewMockInterface(mockCtrl)
})
Context("when the node label is in the input set", func() {
It("recurses right", func() {
myTree.Train(il.Interface(id3InputSet), "3")
})
Describe("Training a Decision Tree", func() {
It("it uses ID3 to maximize entropy", func() {
Expect(myTree.Value()).To(Equal("2"))
Expect(myTree.Left().Value()).To(Equal("1"))
})
It("doesn't continue building a branch if a decision can be made", func() {
Expect(myTree.Left().Right().Right()).To(BeNil())
})
It("builds a tree with the right decisions", func() {
Expect(myTree.Left().Right().Value()).To(Equal(true))
Expect(myTree.Left().Left().Value()).To(Equal(false))
Expect(myTree.Right().Value()).To(Equal(false))
})
})
Describe("Making a decision", func() {
It("decides false in the right cases", func() {
Expect(myTree.Decide([]string{"0", "1"})).To(Equal(true))
})
It("decides true in the right cases", func() {
Expect(myTree.Decide([]string{"2"})).To(Equal(false))
})
})
})