Machine learning is an artificial intelligence (AI) discipline geared toward the technological development of human knowledge. Machine learning allows computers to handle new situations via analysis, self-training, observation, and experience. Machine learning facilitates the continuous advancement of computing through exposure to new scenarios, testing, and adaptation while employing pattern and trend detection for improved decisions in subsequent (though not identical) situations.
Steps in Machine Learning
There are 5 basic steps used to perform a machine-learning task:
- Collecting data:
- Preparing the data
- Training a model: This step involves choosing the appropriate algorithm and representation of data in the form of the model. The cleaned data is split into two parts: train and test (proportion depending on the prerequisites); the first part (training data) is used for developing the model. The second part (test data), is used as a reference.
- Evaluating the model
- Improving the performance.
History and Relationship of Machine Learning to other Fields
Arthur Samuel, an American pioneer in the field of computer gaming and artificial intelligence, coined the term "Machine Learning" in 1959 while at IBM. As a scientific endeavor, machine learning grew out of the quest for artificial intelligence. Already in the early days of AI as an academic discipline, some researchers were interested in having machines learn from data. They attempted to approach the problem with various symbolic methods, as well as what was then termed "neural networks"; these were mostly perceptrons and other models that were later found to be reinventions of the generalized linear models of statistics. Probabilistic reasoning was also employed, especially in automated medical diagnosis.
However, an increasing emphasis on the logical, knowledge-based approach caused a rift between AI and machine learning. Probabilistic systems were plagued by theoretical and practical problems of data acquisition and representation. By 1980, expert systems had come to dominate AI, and statistics was out of favor. Work on symbolic/knowledge-based learning did continue within AI, leading to inductive logic programming. Still, the more statistical line of research was now outside the field of AI proper in pattern recognition and information retrieval. Neural network research had been abandoned by AI and computer science around the same time. This line, too, was continued outside the AI/CS field as "connectionism" by researchers from other disciplines, including Hopfield, Rumelhart, and Hinton. Their main success came in the mid-1980s with the reinvention of backpropagation.
Machine learning was reorganized as a separate field and flourished in the 1990s. The field changed its goal from achieving artificial intelligence to tackling solvable problems practically. It shifted focus away from the symbolic approaches it had inherited from AI and toward methods and models borrowed from statistics and probability theory. It also benefited from the increasing availability of digitized information and the ability to distribute it via the Internet.
Relation to Data mining
Machine learning and data mining often employ the same methods and overlap significantly. Still, while machine learning focuses on prediction based on known properties learned from the training data, data mining focuses on discovering (previously) unknown properties in the data (this is the analysis step of knowledge discovery in databases). Data mining uses many machine learning methods but with different goals; on the other hand, machine learning also employs data mining methods as "unsupervised learning" or as a preprocessing step to improve learner accuracy. Much of the confusion between these two research communities (which do often have separate conferences and separate journals, ECML PKDD being a major exception) comes from the basic assumptions they work with: in machine learning, performance is usually evaluated with respect to the ability to reproduce known knowledge, while in knowledge discovery and data mining (KDD), the key task is the discovery of previously unknown knowledge. Evaluated with respect to known knowledge, an uninformed (unsupervised) method will easily be outperformed by other supervised methods. In contrast, in a typical KDD task, supervised methods cannot be used due to the unavailability of training data.
Relation to Optimization
Machine learning also has intimate ties to optimization: many learning problems are formulated to minimize some loss function on a training set of examples. Loss functions express the discrepancy between the predictions of the model being trained and the actual problem instances (for example, in classification, one wants to assign a label to instances, and models are trained to correctly predict the pre-assigned labels of a set of examples). The difference between the two fields arises from the goal of generalization. While optimization algorithms can minimize the loss on a training set, machine learning is concerned with minimizing the loss on unseen samples.
Relation to Statistics
Machine learning and statistics are closely related fields. According to Michael I. Jordan, the ideas of machine learning, from methodological principles to theoretical tools, have had a long pre-history in statistics. He also suggested the term data science as a placeholder to call the overall field.
Leo Breiman distinguished two statistical modeling paradigms: data model and algorithmic model, wherein "algorithmic model" means more or less the machine learning algorithms like Random forest.
Some statisticians have adopted methods from machine learning, leading to a combined field called statistical learning.
Requirements to Create Good Machine Learning Systems
- Data preparation capabilities.
- Algorithms – Basic and Advanced.
- Automation and Iterative Processes.
- Ensemble Modeling.
Machine Learning Basic Concepts
There are many different types of machine learning algorithms, with hundreds published each day, and they’re typically grouped by either learning style (i.e., supervised learning, unsupervised learning, semi-supervised learning) or by similarity in form or function (i.e., classification, regression, decision tree, clustering, deep learning, etc.). Regardless of learning style or function, all combinations of machine learning algorithms consist of the following:
- Representation (a set of classifiers or the language that a computer understands)
- Evaluation (aka objective/scoring function)
- Optimization (search method; often the highest-scoring classifier, for example; there are both off-the-shelf and custom optimization methods used)
The fundamental goal of machine learning algorithms is to generalize beyond the training samples i.e., successfully interpret data that it has never ‘seen’ before.
Machine Learning Methods
Machine learning algorithms are often categorized as supervised or unsupervised.
- Supervised Machine Learning algorithms can apply what has been learned in the past to new data using labeled examples to predict future events. Starting from analyzing a known training dataset, the learning algorithm produces an inferred function to predict the output values. The system is able to provide targets for any new input after sufficient training. The learning algorithm can also compare its output with the correct, intended output and find errors in order to modify the model accordingly.
- In contrast, unsupervised machine learning algorithms are used when the information used to train is neither classified nor labeled. Unsupervised learning studies how systems can infer a function to describe a hidden structure from unlabeled data. The system doesn’t figure out the right output, but it explores the data and can draw inferences from datasets to describe hidden structures from unlabeled data.
- Semi-supervised machine learning algorithms fall somewhere between supervised and unsupervised learning since they use both labeled and unlabeled data for training – typically a small amount of labeled data and a large amount of unlabeled data. The systems that use this method are able to improve learning accuracy considerably. Usually, semi-supervised learning is chosen when the acquired labeled data requires skilled and relevant resources in order to train it / learn from it. Otherwise, acquiring unlabeled data generally doesn’t require additional resources.
- Reinforcement machine learning algorithms is a learning method that interacts with its environment by producing actions and discovering errors or rewards. Trial and error search and delayed reward are the most relevant characteristics of reinforcement learning. This method allows machines and software agents to automatically determine the ideal behavior within a specific context in order to maximize its performance. Simple reward feedback is required for the agent to learn which action is best; this is known as the reinforcement signal.
Machine learning enables the analysis of massive quantities of data. While it generally delivers faster, more accurate results in order to identify profitable opportunities or dangerous risks, it may also require additional time and resources to train it properly. Combining machine learning with AI and cognitive technologies can make it even more effective in processing large volumes of information.
Machine Learning Applications
Machine Learning actually is everywhere. From Research and Development to improve the business of Small Companies.
Machine Learning: The Expected
Below are some places where you might expect Machine Learning to play a part.
- Speech Recognition (Natural Language Processing in more technical terms): You talk to Cortana on Windows Devices. But how does it understand what you say? Along comes the field of Natural Language Processing, or N.L.P. It deals with studying interactions between Machines and Humans via Linguistics. Guess what is at the heart of NLP: Machine Learning Algorithms and Systems ( Hidden Markov Models being one).
- Computer Vision: Computer Vision is a subfield of AI that deals with a Machine’s (probable) interpretation of the Real World. In other words, all Facial Recognition, Pattern Recognition, and Character Recognition Techniques belong to Computer Vision. And Machine Learning, once again, with its wide range of Algorithms, is at the heart of Computer Vision.
- Google’s Self-Driving Car: Well. You can imagine what drives it, actually. More Machine Learning goodness.
But these were expected applications. Even a naysayer would have a good insight about these feats of technology being brought to life by some “mystical (and extremely hard) mind crunching Computer wizardry.”
Machine Learning: The Unexpected
Below are some places normal folks would not really associate easily with Machine Learning:
- Amazon’s Product Recommendations: Ever wondered how Amazon always has a recommendation that just tempts you to lighten your wallet? Well, that’s a Machine Learning Algorithm(s) called “Recommender Systems” working in the backdrop. It learns every user’s personal preferences and makes recommendations according to that.
- Youtube/Netflix: They work just as above!
- Data Mining/Big Data: This might not be so much of a shock to many. But Data Mining and Big Data are manifestations of studying and learning from data at a larger scale. And wherever there’s the objective of extracting information from data, you’ll find Machine Learning lurking nearby.
- Stock Market/Housing Finance/Real Estate: All of these fields incorporate a lot of Machine Learning systems in order to better assess the market, namely “Regression Techniques,” for things as mediocre as predicting the price of a house to predicting and analyzing stock market trends.
Artificial Intelligence (AI)
Artificial Neural Network (ANN)