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Usted está aquí: Second assignment, part I: Notebook for the first part of the second assignment

# Second assignment, part I: Notebook for the first part of the second assignment

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Autor: Ricardo Aler

# SECOND ASSIGNMENT. MACHINE LEARNING WITH SCIKIT-LEARN.¶

## PART I (1.5 POINTS)¶

The aim of part I of the Scikit-learn assignment is for you to self-learn and get used to this Machine Learning tool. The main part (part II) of the assignment will be explained next week (11/12).

Here, you will learn to:

• Perform a crossvalidation on the iris classification problem with decision trees (so far, we have only done regression)
• Perform a crossvalidation on the iris classification problem with KNN (I haven't explained this, you will have to learn how to use it from the web)
• Perform grid search in order to determine the best value for hyper-parameter K

You will also have to go through two notebooks I have prepared for you in order to see how crossvalidation and hyper-parameter tuning are used in Scikit-learn

# 0. Carry out the "DECISION TREES WITH A TRAINING AND A TESTING SET AND CROSSVALIDATION" notebook and understand the main ideas¶

## 1. Perform a crossvalidation on the iris classification problem with decision trees:¶

It is important to remember that for classification, you have to use

• clf = tree.DecisionTreeClassifier() # for constructing the classifier
• metrics.accuracy # for computing error
In [7]:
```# Write code here
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## 2. Perform a crossvalidation on the iris classification problem with KNN¶

I haven't explained how to use KNN in Scikit-learn. You will have to read and obtain the relevant information here

In [8]:
```# Write code here
```

## 3. Try different values for K (KNN) - change them by hand- and see if you obtain a better result than with KNN default value. Always use crossvalidation.¶

In [9]:
```# Write code here
```

## 5. USE GRID SEARCH AND RANDOMIZED SEARCH TO FIND THE OPTIMAL VALUE FOR K¶

In [10]:
```# Write code here
```

# 6. OPTIONAL (you may get 0.25 extra points if you decide to do this).¶

K is the main hyper-parameter of KNN. Find another hyper-parameter that you consider relevant, and try to optimize both K and the other parameter using grid-search. Are you able to improve on previous results?

In [11]:
```# Write code here (optional)
```
In [ ]:
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