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Jure Leskovec, Stanford University - SNAP - Stanford University

Jure Leskovec, Stanford University - SNAP - Stanford University

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Building decision trees<br />

using MapReduce<br />

How to predict?<br />

Predictor: avg. y i of the<br />

examples in the leaf<br />

When to stop?<br />

# of examples in the leaf is small<br />

How to build?<br />

One MapReduce job per level<br />

Need to compute split quality<br />

for each attribute and each split<br />

value for each current leaf<br />

3/9/2011 <strong>Jure</strong> <strong>Leskovec</strong>, <strong>Stanford</strong> C246: Mining Massive Datasets 29<br />

|D|=10<br />

A<br />

|D|=90<br />

.42 B<br />

X1

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