gistfile1.txt

from math import log 

def calcShannonEnt(dataSet): 
    numEntries = len(dataSet) 
    labelCounts = {}
    for featVec in dataSet: 
        currentLabel = featVec[-1]
        if currentLabel not in labelCounts.keys(): 
        labelCounts[currentLabel] = 0 
        labelCounts[currentLabel] += 1 
    shannonEnt = 0.0 
    for key in labelCounts: 
        prob = float(labelCounts[key])/numEntries 
        shannonEnt -= prob * log(prob,2) 
    return shannonEnt 
    
def createDataSet(): 
       dataSet = [[1, 1, 'yes'], 
       		   [1, 1, 'yes'],
       		   [1, 0, 'no'], 
       		   [0, 1, 'no'], 
       		   [0, 1, 'no']]
	    labels = ['no surfacing', 'flippers'] 
      return dataSet, labels