A Survey of Machine Learning Algorithms is a paper written by researchers at Google. The paper provides a detailed overview of different machine learning algorithms and their performance on various datasets.

For more information check out our video:

## Introduction

Machine learning is a rapidly growing field of computer science that is providing new insight into how computers can learn from data. This survey provides an overview of the main machine learning algorithms, including linear models, decision trees, artificial neural networks, and ensemble methods. It also discusses the main issues that need to be considered when applying machine learning algorithms, such as model selection, overfitting, and data preprocessing.

## Linear Regression

Linear regression is a supervised machine learning algorithm where the predicted output is continuous and has a constant slope. It’s used to predict values within a continuous range, (e.g. house price) rather than trying to classify them into categories (e.g. cat, dog). Linear regression is also simple to understand and easy to implement, which makes it a popular choice among practitioners.

There are two main types of linear regression – simple linear regression and multiple linear regression. Simple linear regression only has one explanatory variable, while multiple linear regression has two or more.

Linear regression can be used for both classification and prediction problems. For classification, the target variable can be dichotomous (e.g. survived/not survived) or categorical (e.g. A/B/C). For prediction, the target variable is continuous (e.g. predicting rent price).

The main advantages of linear regression are that it’s straightforward and easy to interpret, it can be used for both classification and prediction problems, it’s highly scalable, andno assumptions need to be made about the distribution of the data.

The main disadvantages of linear regression are that it cannot model non-linear relationships, it’s vulnerable to outliers,and it can be biased if there are collinearity in the data

## Logistic Regression

Logistic regression is a machine learning algorithm that is used to predict the outcome of a binary dependent variable, based on a set of independent variables. The dependent variable can take on one of two values, 0 or 1, which represent the two possible outcomes of the dependent variable. The independent variables can be categorical or numerical.

Logistic regression is a supervised learning algorithm, which means that it is given a training dataset of known outcomes in order to learn the relationship between the independent and dependent variables. Once the algorithm has learned this relationship, it can then be applied to new data in order to predict the outcome of the dependent variable.

There are a few different ways to perform logistic regression, including maximum likelihood estimation and gradient descent. Maximum likelihood estimation estimates the coefficients of the independent variables by maximizing the likelihood function. Gradient descent calculates the coefficients by taking steps in the direction that maximizes the likelihood function. There are also a few different ways to regularize logistic regression, which can help prevent overfitting.

Logistic regression is a powerful tool for prediction and classification, and it can be used for a variety of applications such as credit scoring, medical diagnosis, and market segmentation.

## Support Vector Machines

In machine learning, support vector machines (SVMs) are a set of supervised learning methods used for classification, regression and outliers detection.

The advantages of support vector machines are:

-They are effective in high dimensional spaces.

-They are still effective in cases where the number of dimensions is greater than the number of samples.

– They use a subset of training points in the decision function (called support vectors), so it is also memory efficient.

– They can be used for non-linear classification by using the kernel trick, implicitly mapping their inputs into high dimensional feature spaces.

The disadvantages of support vector machines include:

– If the number of features is much greater than the number of samples, the method is likely to give poor performances.

– SVMs do not directly provide probability estimates, these can be calculated from decision values (see above).

## Decision Trees

Decision trees are a popular type of machine learning algorithm. They are powerful and easy to use, making them a good choice for many tasks. Decision trees are also very efficient, meaning they can handle large amounts of data very quickly.

Decision trees work by making decisions based on the data. Each decision is made by comparing two values. The first value is the value of the attribute (or feature) that we are testing. The second value is a threshold value. If the first value is greater than or equal to the threshold, then we make one decision. If it is less than the threshold, then we make another decision.

This process continues until we reach a final decision. In this way, decision trees can be used for classification tasks (such as determining whether an email is spam or not), or for regression tasks (such as predicting stock prices).

There are many different types of decision tree algorithms, but they all share the same basic structure. In this section, we will discuss some of the most popular algorithms, including CART, ID3, and C4.5.

## Neural Networks

Neural networks are a type of machine learning algorithm that are used to model complex patterns in data. Neural networks are similar to other machine learning algorithms, but they are composed of a large number of interconnected processing nodes, or neurons, that can learn to recognize patterns of input data.

Neural networks are trained using a set of training data, and they can be used to make predictions about new data. Neural networks are often used for tasks such as image recognition and speech recognition.

## Ensemble Methods

Ensemble methods are a powerful category of machine learning algorithms that allow you to combine the predictions of multiple base models into a single overall prediction.

The basic idea behind ensemble methods is that they can provide a better answer than any individual model by harnessing the collective power of multiple models. This is because the individual models in an ensemble can focus on different aspects of the data and can therefore complement each other.

Ensemble methods are particularly well suited to problems where there is a large amount of training data available, as they can make use of all of this data to improve their predictions.

There are a number of different types of ensemble methods, but they can broadly be divided into two categories:

* Averaging Methods: These methods build multiple base models and then combine their predictions by taking the average (or weighted average) of the predictions. Averaging methods include bagging and boosting.

* Voting Methods: These methods build multiple base models and then combine their predictions by using a voting scheme. Voting methods include majority voting and plurality voting.

## Dimensionality Reduction

Reducing the dimensionality of data can be incredibly useful for a variety of machine learning tasks. By reducing the number of features in your data, you can make your models run faster and be more accurate. Dimensionality reduction can also help you to visualize your data better. In this article, we will survey some of the most popular dimensionality reduction algorithms.

-PCA: Principal Component Analysis is one of the most popular dimensionality reduction algorithms. It works by finding the directions in which your data varies the most, and then projecting your data onto those directions.

-SVD: Singular Value Decomposition is another popular Dimensionality Reduction algorithm that can be used for both visualization and datamining tasks.

-Random Forests: Random Forests are a powerful machine learning algorithm that can be used for both classification and regression tasks. They work by training a number of decision trees on a dataset, and then averaging the predictions of those trees.

-XGBoost: XGBoost is a recent addition to the machine learning world, and has quickly become one of the most popular tools for predictive modeling. It works by training a gradient boosting model on your data.

## Feature Selection

Feature selection is a process whereby a machine learning algorithm selects a subset of features from the data set that it believes are most relevant to predicting the target variable. Feature selection algorithms typically search for a combination of features that maximizes some metric (e.g., accuracy, precision, recall, etc.) while minimize other metrics (e.g., number of features, training time, etc.). Some feature selection methods are specific to certain machine learning algorithms (e.g., wrappers), while others can be used with any machine learning algorithm (e.g., filters).

## Model Selection and Hyperparameter Tuning

Selecting the right model is critical to the success of any machine learning project. In this section, we’ll explore some of the most popular machine learning algorithms and look at how to select the right one for your project. We’ll also touch on the importance of hyperparameter tuning, which can be a key factor in getting the most out of your chosen algorithm.

Keyword: A Survey of Machine Learning Algorithms