xväärtused

Xväärtused, or X-values, refer to the input values of a function or the independent variables in a dataset. In a function f: X → Y, the set X is the domain, and the elements x ∈ X are called X-values. When X is a real line, the X-values are real numbers; for multivariate functions, X is R^n and X-values are n-dimensional vectors.

In mathematics, X-values determine the input for which the function yields an output Y. They define the domain over which the function is defined and analyzed. In plotting, X-values are plotted on the horizontal axis and paired with corresponding Y-values (the outputs) to form a graph.

In data analysis and machine learning, X-values typically refer to the features or input variables of observations. For a dataset with n observations and p features, X is commonly represented as an n-by-p matrix, where each row is an observation and each column is a feature. Models such as regression, classification, and clustering use X-values as predictors to estimate or infer Y-values (targets).

Handling and processing X-values is a key step in data workflows. This can include dealing with missing values, encoding categorical features, and scaling numeric features (normalization or standardization). The distinction between X-values and Y-values (outputs, dependent variables) is central to modeling, evaluation, and interpretation.

See also: Y-values, domain, independent variable, feature, predictor, input data.