Distinguish Wild Mushrooms with Decision Tree

Shiqin Yan

Objective Utilize the already existed database of the

mushrooms to build a decision tree to assist the process of determine the whether the mushroom is poisonous.

DataSet Existing record drawn from the Audubon

Society Field Guide to North American Mushrooms (1981) . G. H. Lincoff (Pres. ), NewYork: Alfred A. Knopf

Number of Instances: 8124 (classified as either edible or poisonous)

Number of Attributes: 22 Training: 5416, Tuning: 1354, Testing: 1354 Missing attribute values: 2480 (denoted by

“?”), all for attribute 11

Mushroom Features 1. cap-shape: bell=b, conical=c, convex=x,

flat=f, knobbed=k, sunken = s 2. cap-surface: fibrous=f, grooves=g,

scaly=y, smooth=s 3. cap-color: brown=n, buff=b, cinnamon=c,

gray=g, green=r, pink=p, purple=u, red=e, white=w, yellow=y

4. bruise?: bruises=t, no=f 5. odor: almond=a, anise=l, creosote=c,

fishy=y, foul=f …

Approach Mutual information to determine the features

used to split the tree.

Mutual information: Y: label, X: feature Choose feature X which maximizes I(Y;X)

Most informative features extracted from decision tree: odor spore-print-color habitat population

Prior Research

by Wlodzislaw Duch, Department of Computer Methods, Nicholas Copernicus University

Add cross-validation to improve the accuracy

Prune the tree to avoid over-fitting

Future