1. Random forest
Random forests are collections of trees, all slightly different. To say it in simple words: A random forest classifier builds multiple decision trees and merges them together to get a more accurate and stable prediction. It generally improves decision trees’ decisions.
The greater number of trees in the forest leads to higher accuracy and prevents the problem of overfitting.
Random Forest works in two-phase first is to create the random forest by combining N decision trees, and second is to make predictions for each tree created in the first phase.
The Working process can be explained in the below steps and diagram:
Step-1: Select random K data points from the training set.
Step-2: Build the decision trees associated with the selected data points (Subsets).
Step-3: Choose the number N for decision trees that you want to build.
Step-4: Repeat Step 1 & 2.
Step-5: For new data points, find the predictions of each decision tree, and assign the new data points to the category that wins the majority votes.
The working of the algorithm can be better understood by the below example:
Example: Suppose there is a dataset that contains multiple fruit images. So, this dataset is given to the Random forest classifier. The dataset is divided into subsets and given to each decision tree. During the training phase, each decision tree produces a prediction result, and when a new data point occurs, then based on the majority of results, the Random Forest classifier predicts the final decision.
Consider the below image:
The basic parameters that are used in random forest classifiers are the total numbers of trees, minimum spilt, spilt criteria, etc. Sklearn package in python offers several different parameters that you can check here.