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KMeans Clustering Guide: Techniques, Use cases & Best Practices

MarkovML
April 9, 2024
7
min read

Introduction to KMeans Vector Analysis

Amongst all the unsupervised machine learning algorithms, KMeans clustering is perhaps the simplest and most popular algorithm.

KMeans clustering algorithms work by grouping similar data points to discover the underlying patterns. To do this, the KMeans algorithm searches for a fixed number of clusters within the dataset.

In machine learning models, unsupervised algorithms draw inferences from the existing datasets using the vectors that are sent as input. These algorithms do not refer to any known or labeled outcomes to generate the output.

In short, the KMeans algorithm works by “k” number of cluster-centroids, maps the vectors to the nearest clusters, and averages the data (hence, K-Means) to get the results.

Understanding KMeans Vector Analysis Techniques

The KMeans vector analysis depends on vector representations of input data. Vector representation is the numerical form of the input data that machine learning algorithms transform to process complex data. Each vector represents an attribute or feature of the data which helps the algorithms process it.

For example, the data point shown below is transformed into its vector representation:

Original Data Point:

[Text: "Hello, how are you today?"]

Vector Representation:

[0.2, 0.1, 0.3, 0.5, 0.4, 0.2, 0.6, 0.1, 0.7, ...]

The original data points are transformed into their vector representation using techniques like one-hot encoding, word embeddings, or term frequency-inverse document frequency (TF-IDF).

The KMeans algorithm works in an iterative process to achieve the least deviations in the cluster values. It is executed in three distinct steps. 

Steps in KMeans Vector Analysis

Source

1. Initialization 

In this step, the KMeans algorithm selects a handful of random centroids as the starting point for the iterations. The number of centroids (the value k) is user-defined.

2. Assignment

The algorithm then assigns each data point to the closest centroid based on a distance metric, typically the Euclidean distance. This step helps partition the input data into ‘k’ clusters depending on the positions of the centroids.

3. Update

In the third step, the algorithm recalculates the centroid positions based on the means of the data points that were assigned to each cluster. The new centroid positions now become the mean of all data points assigned to the clusters.

The centroids now move to the center of their respective clusters, achieving a more optimized in-cluster variance.

Evaluation Metrics for KMeans Clustering

You can use several evaluation metrics for KMeans clustering:

  • Inertia, or within-cluster sum of squares (WCSS): This measures the sum of distances squared to their closest centroid. Lower inertia means the clusters are tighter.
  • Silhouette score: This measures how similar an object is to its cluster compared to other clusters. It ranges from (-1) to (1), and a higher score means the object is well-matched.
  • Davis-Boudin index: It measures the average similarity between each cluster and a similar cluster. Lower values indicate good clustering and close-to-zero values indicate well-separated clusters.
  • Gap statistics: It compares the within-cluster dispersion of data to a reference distribution, like uniform distribution or random data permutation. You can use this to determine the optimal number of clusters.

 Applications of KMeans Vector Analysis

Several real-life applications use KMeans algorithms for vector analysis:

1. Image Segmentation and Clustering

KMeans clustering is extremely useful in image segmentation. The algorithm uses the color values of each pixel in an image as feature vectors, grouping them into clusters for processing. It divides the image into regions that are similar in color, enabling it to perform tasks such as object detection and background removal.

2. Document and Text Clustering

KMeans algorithms perform document and text clustering by representing each document as a numerical vector based on word frequencies or embeddings. The algorithm then clusters together all the similar documents to perform tasks such as topic modeling, document classification, and sentiment analysis. It helps with document organization and creating collections.

3. Customer Segmentation in Marketing

KMeans algorithms are used in customer segmentation by treating customers as a feature vector based on aspects like demographic, transactional, or behavioral data. Similar customers are then grouped into segments which allows businesses to polish and target their marketing campaigns, personalize recommendations, enhance customer engagement, and optimize marketing strategies.

4. Anomaly Detection in Data Analysis

In anomaly detection, the KMeans algorithm works by clustering together the data that represents normal behavior. The data points identified as straying from these clusters are subsequently marked as anomalies, instances of fraud, or other undesirable events. The algorithm measures the distance of each data point from its nearest cluster centroid for calculating the degree of deviation.

5. Social Network Analysis and Community Detection

KMeans algorithms help in social network analysis by representing individuals or nodes as a feature vector based on their interactions, connections, or other attributes. The algorithm then groups these nodes into similar clusters or communities that reveal underlying patterns inside that network. It helps with understanding network dynamics, detecting cohesive communities, enhancing social network insight, and more.

Advanced Techniques in KMeans Vector Analysis

There are four key advanced techniques used in the KMeans vector analysis:

1. Dimensionality Reduction with PCA

Principal Component Analysis (PCA) is a technique used to reduce dimensionality by transforming high-D data into lower-dimensional space while preserving its variance. It helps reduce the complexity of computations and improves clustering performance by focusing on the highest-quality features. This way, the clustering results are more efficient and accurate.

2. Handling Non-Numeric Data with One-Hot Encoding

One-hot encoding converts categorical variables into binary vectors. Each category then becomes a binary feature that is represented as 0s and 1s. 0 indicates the absence of a category while 1 indicates the presence of a category. KMeans algorithms are thus able to process non-numeric data effectively while clustering.

3. Handling Large Datasets with Mini-Batch KMeans

Mini-batch KMeans involves partitioning large datasets into mini batches to perform KMeans clustering individually on each batch. Using this approach, it is possible to reduce computational overheads as well as a system's memory usage. This technique makes it easier to process large amounts of data within the budget, resources, and time available.

4. Addressing Imbalanced Data in Clustering

To cluster imbalances in data, KMeans techniques such as oversampling, undersampling, and using less-sensitive clustering algorithms (like DBSCAN) can be used. It further helps to adjust the clustering evaluation metrics to account for class distribution by interpreting the clustering results with high accuracy.

Case Studies and Practical Examples

You can see many practical examples of KMeans clustering in real life:

1. Clustering News Articles by Topic

News and media agencies frequently use KMeans clustering to club articles of similar topics together. The algorithms represent each article as a numerical vector based on word frequencies or embeddings. The algorithms then club similar articles by identifying common themes or topics within the dataset.

2. Segmenting Customer Behavior for Targeted Marketing

Businesses that wish to target specific customers use KMeans algorithms to segment them based on their behavior on the brand channels. The customers are represented as feature vectors based on their behavior metrics. The businesses then tailor campaigns separately for each cluster of customers whose behavior metrics are similar.

3. Identifying Fraudulent Activities in Financial Transactions

Businesses or institutions that deal with financial data leverage KMeans algorithms to determine fraudulent transactions. They do this by representing transactions as numerical vectors based on transaction amount, location, and frequency. Similar transactions are then grouped into clusters to help identify outliers or unusual patterns that require flagging.

Best Practices and Considerations

Here are some recommended practices for optimal results in KMeans vector analysis:

1. Determining Optimal Number of Clusters

It is best to refrain from using too many clusters for KMeans. You can use techniques like the elbow method or silhouette analysis to identify the threshold beyond which adding more clusters isn’t helping enhance the clustering quality.

2. Handling Noisy Data and Outliers

To handle datasets that have a lot of noise, it is best to employ techniques such as outlier detection and removal or use robust clustering like DBSCAN to mitigate the effect of outliers on the results.

3. Interpreting and Validating Results

It helps to assess cluster coherence and evaluate the separation between two clusters using metrics like the Davis-Boudin index. These visualizations help with understanding and validating the quality of cluster plots.

Conclusion

KMeans vector analysis is an important technique businesses can use to uncover hidden insights and key information from within large volumes of their daily data. It leads to informed decision-making, creating targeted and effective marketing strategies, and optimizing resource allocation.

Evolution is ongoing in the field, and the future promises the capability of KMeans vector analysis to handle high-dimensional and streaming data. Integration with deep learning techniques can enable enhanced interpretability and scalability for various applications.

It also helps indirectly enhance customer experiences and ultimately drives business growth. Your business can create its ML model for KMeans analysis using MarkovML’s robust platform.

With MarkovML, your business can benefit from creating responsible AI that can be used for the evaluation of business risks, regulation compliance, and more. Visit MarkovML to understand the full scope of solutions that can help your business do more with its data.

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