Klassifizierungsalgorithmus

Klassifizierung (classification) is the process of organizing objects, terms, or observations into groups, or classes, that share certain characteristics or meet predefined criteria. The aim is to bring order to complex data, facilitate communication, and support decision making. Classifications can be descriptive, describing inherent structure, or prescriptive, defining categories for rules or actions.

Historically, classification has roots in natural history and taxonomy. Carl Linnaeus developed a hierarchical system for organizing living species, a model later extended to medicine, libraries, and information systems. In the 20th century, standardized taxonomies and ontologies emerged to support data exchange and interoperability. With the rise of data science, classification expanded to automated methods, including supervised learning, unsupervised learning, and rule-based approaches.

Common types include hierarchical classification, where categories are arranged in a tree, and flat or multi-label classification, where items may belong to multiple categories. Supervised learning uses labeled data to train models, while unsupervised learning discovers structure in unlabeled data. Methods range from traditional algorithms such as decision trees, random forests, support vector machines, and neural networks to clustering techniques like k-means and hierarchical clustering. In biology, classification often relies on genetic or phenotypic data; in information science, text and image data are categorized using learned representations.

Applications span biodiversity catalogs, medical diagnosis, spam filtering, sentiment analysis, image and speech recognition, product categorization, and risk assessment. Key challenges include data quality, class imbalance, concept drift, and biases. Evaluation typically uses metrics such as accuracy, precision, recall, F1 score, and ROC-AUC, with validation through cross-validation or held-out test sets. See also taxonomy, ontology, and machine learning.