A method is performed at a computer. The computer retrieves a dataset having a plurality of fields, including a first field and a second field. The computer displays a graphical user interface, including a first region displaying the plurality of fields from the dataset, a second region having a plurality of shelves determined according to a user-selected data visualization type, and a third region for displaying one or more data visualizations. The computer receives user actions to drop the first field on a first shelf and to drop the second field on a second shelf. The first and second shelves define positional attributes of data marks. The computer displays a data visualization in the third region. Each data mark has a position in the data visualization determined according to the first shelf, a data value for the first field, the second shelf, and a data value for the second field.