Daily Archives: Jan 28, 2019


Building Decision Tree model in python from scratch – Step by step

In previous post, we created our first Machine Learning model using Logistic Regression to solve a classification problem. We used “Wisconsin Breast Cancer dataset” for demonstration purpose. Now, in this post “Building Decision Tree model in python from scratch – Step by step”, we will be using IRIS dataset which is a standard dataset that comes with Scikit-learn library. Let’s have a quick look at IRIS dataset.

The IRIS dataset

The IRIS dataset is a multi-class classification dataset introduced by British statistician and biologist Ronald Fisher in 1936. This dataset has 150 observations which consists 50 samples of each of three species of Iris flower which are “setosa“, “versicolor” or “virginica“. It is a standard, cleansed and preprocessed multivariate dataset which comes preloaded with Scikit-learn library. Each sample has four input features which are:

  1. Sepal length (cm)
  2. Sepal width (cm)
  3. Petal length (cm)
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