# 100 Days Of ML Code — Day 010

Jehoshaphat I. Abu
·Jul 19, 2018·

## Recap from Day 010

In day 009, we briefly looked at features and labels. Today, we’ll continue with common classification algorithms.

## Common Classification Algorithms

### Bagged and Boosted Decision Trees

In this section, you’ll learn about Bagged and Boosted Decision Trees as seen in MathWorks’s machine learning pdf section 4.

In these ensemble methods, several “weaker” decision trees are combined into a “stronger” ensemble. A bagged decision tree consists of trees that are trained independently on data that is bootstrapped from the input data Boosting involves creating a strong learner by iteratively adding “weak” learners and adjusting the weight of each weak learner to focus on misclassified examples.

Source: MathWorks — Bagged and Boosted Decision Trees

Best Used…

• When predictors are categorical (discrete) or behave nonlinearly

• When the time taken to train a model is less of a concern

### Discriminant Analysis

“Discriminant analysis builds a predictive model for group membership. The model is composed of a discriminant function (or, for more than two groups, a set of discriminant functions) based on linear combinations of the predictor variables that provide the best discrimination between the groups.” “The functions are generated from a sample of cases for which group membership is known; the functions can then be applied to new cases that have measurements for the predictor variables but have unknown group membership.”

Source: MathWorks — Discriminant Analysis

Best Used…

• When you need a simple model that is easy to interpret

• When memory usage during training is a concern

• When you need a model that is fast to predict

You made it to the end of day 010. Thank you for taking time out of your schedule and allowing me to be your guide on this journey.

Refrence: Mathworks- 90221_80827v00_machine_learning_section4_ebook_v03.pdf