What is keyword extraction?
Keyword extraction, also known as keyword detection or analysis, is a text analysis technique automatically extracts the most relevant words and expressions from a given text. It helps summarize the content and identify the main topics discussed.
Keyword extraction uses machine learning and natural language processing (NLP) to break down human language into a format that machines can understand and analyze. It can be applied to various text data types, such as documents, reports, social media comments, online reviews, etc.
The process involves identifying single words (keywords) or groups of words that form a phrase (key phrases) that best represents the content of the text. This allows users to grasp the main ideas and themes quickly without having to read through the entire text manually.
How does keyword extraction work?
Different techniques are used for automated keyword extraction, ranging from simple statistical approaches to more advanced machine-learning methods.
Statistical approaches
- Word frequency: Lists the most repeated words and phrases within a text.
- Word collocations and co-occurrences: Identifies words that frequently appear together (bi-grams, tri-grams) or have a semantic proximity.
- TF-IDF (term frequency-inverse document frequency): Measures the importance of a word in a document within a collection of documents.
- RAKE (Rapid Automatic Keyword Extraction): Uses stopword lists and phrase delimiters to detect relevant words or phrases.
Linguistic approaches
Utilizes morphological, syntactic, or semantic information about words and their relationships to determine which keywords should be extracted.
Graph-based approaches
Represents text as a graph, where words are vertices connected by edges. The importance of each vertex (word) is determined by measures that consider the graph's structure.
Machine learning approaches
Supervised learning algorithms, such as Conditional Random Fields (CRF), learn patterns by weighting different features in a sequence of words to make predictions.
