Dimensions

A dimension is an axis of the model, such as snapshot or generator. Declarations are indexed by it, and sum reduces over it. A map from one axis onto another is a relation. Whether to declare a column of data as a dimension, a relation or a parameter: declare a column of data.

dimensions

dimensions:
  snapshot: { dtype: int }
  generator: { dtype: str }

Every dimension named anywhere in the file is declared here.

Field
dtype	float, int, str, datetime	default str
description	free text, never parsed	default null

A declaration says that the axis exists and what type its labels have. The dimension holds the authoritative order. Its members arrive with the data, in the order the table gives them. shift, sum_back and position() count along that order, and everything indexed by the dimension is matched to its members by label.