Machine Learning
- Definition
- History
- Types
- Lifecycle
- Real-World Example
- Main challenges
When we think about
machine learning we may think of situations like those described in The
Terminator movie in which machine starts to think on their own like humans and
start a war against humanity, but things like this are still far away from reality
because till now machines can only do one task at a time with precision even
when they are trained on similar data or situation for a long time or with many
data. Therefore, when we think about machine learning operations we think that machines
can think or be able to learn by themselves which is not fully true. Machine
learning is a subfield of artificial intelligence we can say that artificial is
a superset then machine learning is only a part or subset of artificial intelligence but they are both often discussed together. And many times artificial intelligence and machine learning are used interchangeably It allows the systems or computers to
automatically learn from already available data. To do this machine learning
uses various algorithms and mathematical formulas. In this, we will look at
what is machine learning and its types and learn about them, in other words, we learn machine learning basics or we can say it is a machine learning for beginners blog.
First, we need to know what is machine learning.
AI and Machine learning is an area of study in computer science that allows computers the capability to which the computers can learn without being heavily programmed before doing some task. It tries to make computers act like or behave similarly to humans which is the ability to learn. It is very extensively used in today’s world. The term machine learning has been available since around 1959 when it was first used by Arthur Samuel.
Machine learning is the
science or we also can say the art of programming computers which makes them learn
from data. The more general definition would be: that machine learning is the
field of study that gives computers the ability to learn without being
explicitly programmed (Arthur Samuel; 1959).
For a more engineering-oriented definition, we can say that: - A computer
program is said to learn from experience E concerning some task T
and some performance measure P, if its performance on T, as
measured by P, improves with experience E (Tom
Mitchell, 1977).
Machine Learning Examples
Let’s look at a real-world example to better understand machine learning. There is a
megacity, where there is a hospital in which a nurse Sarah is working, and she finds
herself grappling with a common healthcare challenge: patient readmissions. Despite
the hospital’s best efforts to provide quality care, some patients returned
shortly after discharge, mainly due to complications that could have been
prevented with timely interventions.
One Sarah attended a workshop on machine learning
applications in healthcare. Excited by the potential of this technology, she
started a journey to explore how it could help to reduce the readmissions at
her hospital.
Sarah arrived at the hospital's data science
department with a can-do attitude, determined to use machine learning
algorithms to crunch reams of patient data. The data science department and
Sarah examined factors like patient’s medical histories, treatment plans,
demographics, and post-discharge follow-up procedures.
As they went deeper into the data, patterns
started to emerge. The machine learning algorithms or machine learning system design identify several key
predictors of readmission, including the patient’s age, previous
hospitalizations, chronic conditions, and adherence to medication regimens.
Moreover, they find a nuanced relationship between these variables, allowing
for a more comprehensive understanding of readmission risk factors.
With these insights, Sarah and the data science
team devised a proactive strategy to prevent readmissions. They implemented
personalized care plans tailored to each patient’s unique needs, leveraging
machine learning algorithms to predict and mitigate potential risks. For
instance, high-risk patients received additional post-discharged support such
as home visits from healthcare professionals, remote monitoring devices, and
regular check-in calls.
How does machine learning work?
Mainly machine learning
models try to predict the results, for doing prediction it first trains on
previous data and learns from it then tries to predict the new outcome for
unseen data. The more the amount of data the better the model predicts
generally, that is the models’ accuracy increases. By hard coding the problem
we might face many challenges like it is a very complex task and also if we
need to update the code then we need to go through all the written code for
updating it which is costly and time-consuming. In machine learning without
writing the code, we just need to provide the data into the model’s algorithms,
which automatically able to build the logic based on the data and also able to
predict the output. With this process, we can easily update the model if we
have new data when we need to update the model.
Why we should use machine learning?
We should use machine
learning because it reduces the time and cost of tasks that previously took
many lines of code and lots of effort. For example, now our email filters can
filter ham and spam mail without our guidance which is possible because of machine
learning if we try to do this task using the traditional coding approach it
would take lots of time and hard coding even after that if the new type of spam
arrived we need to update the code manually which is a very difficult task and
therefore if we use machine learning we can do this much easily and also for a
new type of spam we need to just train our model with a new type of data which
have these type of spam mails. This is only one example of why we should use
machine learning there are countless options or applications available where we
use machine learning or we might be able to use them in the future. Below are
some key points that show the importance of Machine learning: -
- Instant increment in the production of
data.
- Solving complex problems, which are
difficult for humans like finding patterns in a dataset which have 1000
features.
- Ability to decide on many sectors like
finance, fraud, and anomaly detection.
- Finding hidden patterns and extracting
useful information from data.
Examples of
machine learning applications
- An example of anomaly detection is the examination of product images on a production line to automatically classify them and identify defective products. This process may also include image classification techniques to determine product type or potential defects.
- Detecting tumors in brain scans. It is an example of semantic segmentation in which every pixel of an image (or perhaps a medical image) is classified.
- Automatically classify new articles. It is a natural language process (NLP), in which it can further be classified as a text classifier it can use recurrent neural networks or transformers.
- With the help of machine learning we can automatically detect offensive comments in forums which is achieved by text classification techniques, often using natural language processing (NLP) tools. In this process, we analyze comments to determine if they have offensive language or inappropriate content.
- Automatic summarization of long documents is a natural language processing (NLP) feature that involves compressing large texts into shorter, more concise versions. This process, called text summarization, aims to extract important information from a document while preserving its main points.
- Building a personal assistant or chatbot. It involves several NLP components, such as question-answering modules and natural language understanding (NLU).
- Predicting our company's profit for the next year is also based on various performance metrics achieved by the ML model this type of ML is predictive analytics. In this we need to use multiple regression algorithms, such as linear regression and polynomial regression models, to analyze historical data and predict future revenue trends.
- Developing an application that responds to voice commands requires the introduction of speech recognition technology. This process involves analyzing sound samples to interpret spoken commands. Due to the complexity and long duration of sound sequences, speech recognition is mostly based on deep learning models such as RNNs, CNNs, or transformers.
- Detecting credit card fraud can also done via machine learning methods. It is an example of anomaly detection in which we try to detect uneven patterns in someone’s credit card transaction
Features of Machine Learning
- It can learn from past data and improve
its performance accordingly.
- It can detect many or different patterns
from data.
- It is data-driven technology.
- It is very much similar to data mining
because it can deal with huge amounts of data.
Types of Machine Learning
There are many different classifications
of machine learning but at the broader level we can classify them into four
types:
·
Supervised learning
·
Unsupervised learning
·
Reinforcement learning
·
Semi-supervised learning
Supervised learning
In this, the training set
we feed to the algorithm has solutions these solutions are also called labels. We can
also say that in supervised learning, labeled datasets are given to the machine
learning system for training, and after the training, the system can predict
the results or outcomes.
Gender |
Age |
Weight |
Label |
M |
47 |
68 |
Sick |
M |
68 |
70 |
Sick |
F |
58 |
56 |
Healthy |
M |
49 |
67 |
Sick |
F |
32 |
60 |
Healthy |
M |
34 |
65 |
Healthy |
M |
21 |
74 |
healthy |
In above table contains
the patient’s information that also has a labels data set which is also
called "label" in this and has two options Sick and Healthy.
At very basic supervised
learning can be divided into 2 sub-classes called ‘classification’ and
‘regression’. One good example of classification is filtering spam and spam
emails. In this supervised learning model, we first trained the model with a
large number of example emails with their labels which makes the model able to
learn how to differentiate new emails. Another common task is to predict the
continuous values like the price of a car, house, or stock price prediction.
Let’s look at the most common supervised learning algorithms: -
- K-Nearest Neighbors
- Linear Regression
- Logistic Regression
- Support Vector Machines
- Decision Trees and Random Forests
- Neural Networks and deep learning.
Unsupervised Learning
In this process, we have a dataset but don’t have the labels that is we have unlabeled data. In its algorithms, classification or categorization is not added. We can also say that in unsupervised learning the machine tries to learn from itself without the help of supervision. In this, the machine tries to find useful insights or patterns from the data. Many recommendation systems are used to recommend movies and songs, next purchases are based on unsupervised learning. Clustering is also a good example of unsupervised learning. In this, we can say that the machine uses information that does not have labels or classifiers to allow it to act on that guidance or categories. In this, the main goal of the machine is to group the unorganized information according to similarities, patterns, and differences without any previous training of data.
Gender |
Age |
Weight |
M |
47 |
68 |
M |
68 |
70 |
F |
58 |
56 |
M |
49 |
67 |
F |
32 |
60 |
M |
34 |
65 |
M |
21 |
74 |
In the above table, we
have a dataset but don’t have any labels that help us in supervised learning.
Now in the above dataset, we can try to find the patterns or clusters among the
data. One such cluster can be dividing or sorting the data according to Gender
or also can be done using sorting the data into different age groups. Here are
the most common unsupervised learning and their algorithms: -
·
Clustering
o
K Means
o
DBSCAN
o
Hierarchical Cluster Analysis (HCA)
·
Anomaly detection and novelty detection
o
Isolation Forest
·
Visualization and dimensionality reduction
o
Principal Component Analysis (PCA)
o
Kernel PCA
o
Locally Linear Embedding (LLE)
o
t-Distributed Stochastic NeighborEmbedding (t-SNE)
·
Association rule learning
o
Apriori
o
Eclat
Reinforcement
Learning
It is very different from
both supervised learning and unsupervised learning. In this learning system, we
have an agent or bot that observes the environment and selects an action or
takes an action, this action then either gets a reward or penalty (penalty
meaning negative reward) the model must learn by itself which is the best
strategy for it and maximizes the reward. For example – like when we train
an animal, we reward them for doing a good thing or following our orders and
punish or do not reward them when they don’t follow the order this, we train the animal. We
can imagine the same thing for reinforcement learning. When the bot or agent
behaves well, it gets rewarded; when it behaves poorly, it gets penalized. One
excellent example of reinforcement learning is the AlphaGo software developed
by DeepMind. It is a Go player that made waves in newspapers in 2017 when it
defected the world champion. Through the analysis and self-play of games millions
of times, it learns its winning policies. It is different from supervised
learning in such a way that supervised learning is trained using the labels or
answers which is already available in training data; in contrast, in
reinforcement learning, the model does not have any answers. The model agent
chooses how to proceed with the assigned task. It employs what is known as the
trial-and-error approach. Algorithms that use reinforcement learning are
capable of learning from results and choosing the best course of action. Every
time it takes an action, it evaluates it and gets input from the algorithm to
help it decide if the decision is right or wrong.
Semi-Supervised Learning
Semi-supervised learning is a type of machine learning that falls between supervised and unsupervised learning methods and offers a
solution for situations where there is few labeled data compared to unlabeled data. This approach merges a small set of labeled data with a larger set of unlabeled data during its training process. A
notable example is Google Photos, where the system independently detects faces
from uploaded images, a form of unsupervised learning. However, it asks users
to tag these faces to improve accuracy and user experience, thus adding
supervised learning elements. This combination allows us to more
efficiently organize photos and search based on identified individuals.
Most algorithms that fall
within the category of semi-supervised learning incorporate aspects of both
unsupervised and supervised learning. Deep belief networks (DBNs) are composed
of layers of unsupervised restricted Boltzmann machines (RBMs). Before being
refined as a whole using supervised learning techniques, RBMs go through
several rounds of unsupervised training.
There are also other
types of machine learning types available like instance-based, model-based,
batch learning, online learning, etc.
Machine Learning Lifecycle
The Machine learning
lifecycle involves a series of steps which are: -
Understanding the problem
– it is the first step of the machine-learning process. In this process, we
first try to understand the business problem and define its objective which is
what the model must do.
Data Collection – Once
the problem statement is established, the next step involves gathering the
relevant information needed to build the model. These data sets can be obtained
from a variety of channels, including databases, sensors, application
interfaces (APIs), or web capture technologies.
Data Preparation – only collecting data will not help to make the machine learning model work properly that is when our data is collected it is necessary to check that is, is the data is proper and then convert it into the desired format so we can use it in machine learning model and the model will able to find the hidden patterns. This process has its small sub-processes these are: -
- Data cleaning
- Data Transformation
- Explanatory data analysis and feature engineering
- Split the dataset for training and testing
Model Selection – Selecting the optimal machine-learning algorithm to address the problem comes next after preprocessing the data. Making this decision requires knowledge of the advantages and disadvantages of various algorithms. Many times, it is required to apply many models, evaluate their results, and then choose the best algorithm according to the particular needs of the our job.
Model building and
training – when we select the proper algorithm for our model we need to build
the model. It can be done using below three methods: -
- In the traditional machine learning building approach, we just need to fine-tune some hyperparameter tunings.
- In the field of deep learning, the first step involves sketching the architecture of each layer. This includes defining details such as input and output dimensions, number of nodes in each layer, choice of loss function, optimization of gradient descent, and other related parameters needed to build the neural network.
- At last, after the model is trained using the preprocessed dataset.
Model Evaluation – Once
the training phase is completed, assessing the model's efficacy involves
evaluating its performance on the test dataset. This assessment aids in gauging
accuracy and effectiveness through various methodologies such as generating a
classification report, calculating metrics like F1 score, precision, and recall,
and examining performance indicators like the ROC Curve, Mean Square Error, and
Absolute Error.
Model tuning – after the
training and testing are done, we have the results of the model on the unseen
dataset, now we might need to tune or optimize the algorithms’ hyperparameter
so we can get the optimized result or performance.
Deployment – Once the
model is optimized and its performance meets our expectations, we deploy it to
a production environment where it can make predictions based on fresh,
never-before-seen data. In this implementation phase, the model is integrated
into the existing software infrastructure, or a new system is developed that is
specifically adapted to implement the model.
Monitoring and Maintenance – Following deployment, it's critical to track the model's performance over time, keep an eye on the dataset in the production environment, and do any necessary maintenance. In this process, the model is updated if new data becomes available, retrained as necessary, and data drift is monitored for.
Main Challenges of Machine Learning
In the realm of machine learning, two critical factors often lead to suboptimal outcomes: flawed algorithms and inadequate data. Let's delve into each aspect separately.
Insufficient Training
Data:
To effectively train a
machine learning model, a substantial amount of data is essential. Simple
tasks, such as distinguishing between an apple and a ball, may require
thousands of examples, while more complex endeavors like speech recognition
might demand millions. Unfortunately, numerous fields suffer from limited or
unexplored data, hindering the development of robust machine-learning models.
Nonrepresentative
Training Data:
The quality of training
data is paramount for successful machine learning. It's imperative that the
data provided for training accurately represents the scenarios the model will
encounter in real-world applications. Failure to ensure representativeness can
result in a model that struggles to generalize effectively, leading to poor
predictions or outputs.
Poor-Quality Data:
A model cannot identify important patterns if it is trained on data that is full of mistakes, outliers, or noise. To improve model performance, time and effort must thus be spent cleaning and improving training data.
Irrelevant Features:
Feeding a model with relevant features is as important as saying "Garbage in, garbage out". Selected, extracted, and created features that allow the model to successfully understand the underlying patterns in the data are mostly dependent on feature engineering.
Overfitting:
When a model too closely fits the training data—including noise and outliers—it is said to be overfit. It may do well in training, but in real-world situations, it performs worse since it finds it difficult to generalize to unknown input.
Underfitting:
It occurs when a model does not identify important patterns in the training data, which leads to worse performance during training and when presented with new data..
Additional Limitations:
Machine learning thrives on data diversity and heterogeneity. Algorithms struggle to derive meaningful insights without a sufficient range of variations within the data. For efficient model training, sufficient sample sizes are usually at least 20 observations per group. Moreover, the availability of training data determines the usefulness of machine learning; in the absence of it, the model is idle. Machine learning projects are often hampered by the dearth or lack of variety in data.
In conclusion, successful implementation of machine learning in many fields depends critically on resolving problems with algorithmic defects and data constraints.
No comments:
Post a Comment