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    <title> Errata for Machine Learning in Action</title>
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    <legend>Errata for Machine Learning in Action by Peter Harrington</legend>
<p>
Hi thanks for taking a look at <a href="http://www.manning.com/pharrington"><b>Machine Learning in Action</b></a>.  If you find any errors that are not published below please submit them to the book's
<a href="http://www.manning-sandbox.com/forum.jspa?forumID=728" target="_blank">
Author Online Forum</a>.
</p>

<p>
<h2>On page 17: (not in a code listing)</h2>
The line: </br>
myEye = randMat*invRandMat </br>

should appear above the line:</br>
>>> myEye – eye(4)</br>
</p>


<h2>Listing 2.2 bottom of page 25-page26</h2>
A better version of the function file2matrix() is given below.  The code in the book will work.
<pre>
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
</pre>


<p>
<h2>Page 26:</h2>
datingDataMat, datingLabels = kNN.file2matrix('datingTestSet.txt') </br>
should be:</br>
datingDataMat, datingLabels = kNN.file2matrix('datingTestSet2.txt') </br>
</p>

<p>
>>> datingLabels[0:20]</br>
[‘didntLike’, ‘smallDoses’,……</br>

should be:</br>

>>> datingLabels[0:20]</br>
[3, 2, 1, 1, 1, 1, 3, 3, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 2, 3]</br>
</p>

<h2>Listing 2.5 page 32</h2>
datingDataMat, datingLabels = file2matrix('datingTestSet.txt')</br>
should be:</br>
datingDataMat, datingLabels = file2matrix('datingTestSet2.txt')</br>

<p>
<h2>Page 41 (not a code listing)</h2>
l(x<sub>i</sub>) = log<sub>2</sub>p(x<sub>i</sub>)</br>
Should be:</br>
l(x<sub>i</sub>) = -log<sub>2</sub>p(x<sub>i</sub>) </br>
</p>

<p>
<h2>Page 42: Listing 3.1</h2>
The line:</br>
labelCounts[currentLabel] = 0</br>
should be indented from the lines above and below it.  The code in the repo is correct.
</p>


<h2>Listing 3.3 page 45</h2>
bestFeature = I </br>
should be:</br>
bestFeature = i</br>

<h2>Page 52 (not a code listing)</h2>
>>> treePlotter.retrieveTree(1)</br>
should return:</br>
{'no surfacing': {0: 'no', 1: {'flippers': {0: {'head': {0: 'no', 1: 'yes'}}, 1: 'no'}}}}</br>

<h2>Page 92</h2>
Before the line:</br>
>>> reload(logRegres)</br>
add the line:</br>
>>> from numpy import * </br>
At the beginning of the book I mention that this should be added to every interactive session, but it will be helpful for people to see this line here if they don’t remember that.

<h2>page 104 (not a code listing)</h2>
 |wTx+b|/ ||w||</br>
should be:</br>
|wTA+b|/||w||</br>


<h2>Listing 8.4 page 168</h2>
The line:</br>
returnMat = zeros((numIt,n)) </br>
Should be added before the line: </br>
ws = zeros((n,1)); wsTest = ws.copy(); wsMax = ws.copy()</br>

<h2>Listing 9.5 page 195 </h2>
yHat = mat((m,1))</br>
Should be:</br>
yHat = mat(zeros((m,1)))</br>
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