errata.rst

On page 17: (not in a code listing)

The line:

myEye = randMat*invRandMat

should appear above the line:

>>> myEye – eye(4)

Listing 2.2 bottom of page 25-page26

A better version of the function file2matrix() is given below. The code in the book will work.

def file2matrix(filename):
   fr = open(filename)
   arrayOLines = fr.readlines()
   numberOfLines = len(arrayOLines)
   returnMat = zeros((numberOfLines,3))
   classLabelVector = []
   index = 0
   for line in arrayOLines:
      line = line.strip()
      listFromLine = line.split('\t')
      returnMat[index,:] = listFromLine[0:3]
      classLabelVector.append(int(listFromLine[-1]))
      index += 1
   return returnMat,classLabelVector

Page 26:

datingDataMat, datingLabels = kNN.file2matrix('datingTestSet.txt')

should be:

datingDataMat, datingLabels = kNN.file2matrix('datingTestSet2.txt')

This will result in:

>>> datingLabels[0:20]

[‘didntLike’, ‘smallDoses’,……

appearing as:

>>> datingLabels[0:20]

[3, 2, 1, 1, 1, 1, 3, 3, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 2, 3]

Listing 2.5 page 32

datingDataMat, datingLabels = file2matrix('datingTestSet.txt')

should be:

datingDataMat, datingLabels = file2matrix('datingTestSet2.txt')

Page 41 (not a code listing)

l(xi) = log2p(xi)

Should be:

l(xi) = -log2p(xi)

Page 42: Listing 3.1

The line:

labelCounts[currentLabel] = 0

should be indented from the lines above and below it. The code in the repo is correct.

Listing 3.3 page 45

bestFeature = I

should be:

bestFeature = i

Page 52 (not a code listing)

>>> treePlotter.retrieveTree(1)

should return:

{'no surfacing': {0: 'no', 1: {'flippers': {0: {'head': {0: 'no', 1: 'yes'}}, 1: 'no'}}}}

page 104 (not a code listing)

|wTx+b|/ ||w||

should be:

|wTA+b|/||w||

Listing 8.4 page 168

The line:

returnMat = zeros((numIt,n))

Should be added before the line:

ws = zeros((n,1)); wsTest = ws.copy(); wsMax = ws.copy()

Listing 9.5 page 195

yHat = mat((m,1))

Should be: yHat = mat(zeros((m,1)))