First steps

in Data Mining

with Weka

Łukasz Kobyliński & Radosław Szmit

Codepot 2015

What is Data Mining?

Data Mining is a process of discovering hidden information
in data.

https://visualisingadvocacy.org/blog/disinformation-visualization-how-lie-datavis

Typical applications

Customer analysis

• which customers are likely to increase their purchases?
• which products are more likely to sell to my customers?

Typical applications

Image mining

which images in my collection contain cats? which of my contacts are visible on these photos? what is the sex and age of these people?

Data Mining Methods

• Regression analysis
• Classification
• Cluster analysis
• Association rule mining
• Sequence mining
• Anomaly detection
• ...

Task #1

Assign names to flowers

How do they differ?

iris-versicolor, iris-setosa, iris-virginica

iris-	iris-	iris-

Task #2

Answer the questions:

• iris-setosa has:
• low values of
• high values of
• iris-virginica has:
• low values of
• high values of


• the three classes are best separated by:
• sepallength
• sepalwidth
• petalwidth

Task #3

Use the rules.PART classifier on the iris dataset and answer the questions:

• which is better on this dataset: J48 or PART?
• how many examples of iris-versicolor have been classified as iris-setosa?
• how many examples of iris-virginica have been classified as iris-versicolor?


• what is the accuracy of the classifier on the training set?

Task #4

Use the J48 classifier on the iris dataset and answer the questions:

• use the tree visualization pane to manually perform classification of the following example:
• sepallength=6.7, sepalwidth=3.0
• petallength=5.0, petalwidth=1.7
• are all the attributes used in the classifier?


• what are the numbers of instances of type iris-versicolor, which were misclassified as iris-virginica?
  (use the Visualize classifier errors panel).

THE END

Thanks!