Out of the cell block

The conventional spreadsheet represents granular sampling of a conceptual space that is either rectangular or cuboid in form. A worksheet holds data, relational structures, or other information in a two-dimensional array. At the simplest level, data are represented by variable and case, or field and record, in columns and rows respectively. The collection of worksheets - usually known as a workbook, notebook, or something similar - offers limited extension of the same model into a third dimension; how limited depends on the particular product. In practice, of course, this simplest level is normally used only for data storage of the most basic kind; the modern spreadsheet is flexible enough to allow the construction and embodiment of far more complex interrelations. Nevertheless, the fact remains that each cell of a spreadsheet holds a single scalar value. That scalar may represent a text string; it may derive from a web of conditional formulae and conditional tests; but a scalar it remains. And the cell exists within what is still a rectangular or cuboid universe, with its origins in accountancy.

DADiSP remains, conceptually, a spreadsheet - and it still consists of discrete cells - but it breaks apart the structure, and approaches cell relations from a different standpoint. DADiSP cells are like poppet beads. Remember poppet beads? If not, you are perhaps younger than I... poppets were plastic imitation pearls, each with a small hole on one side and a small spherical peg on the other. By plugging the peg of one into the hole in the next, you could assemble them into an imitation pearl necklace of exactly the required length. Or, if you were a child, you could steal them from the parental dressing table and explore the fascinating world of flexible and potentially infinite strings, of various closed and open one-dimensional geometries - until your parents finally gave in and bought you Meccano, Lego, or one of those kits for building molecular models. DADiSP's cells are like that - they come not in a predetermined array, but ready to be strung together in a potentially infinite range of configurations. And each cell can hold not only scalars, but numerous other data structures - including non-reals, vectors, series, or complete data-arrays equivalent to whole worksheets in a conventional model.

I first touched on all this about 18 months ago, fairly briefly, when describing DADiSP as one 'Excel alternative', available for in-line field analysis of convoluted agricultural data ('Looking Beyond Excel', Scientific Computing World, January 2002). The spread of cheap, portable, dispersed computing power has made increasingly common this sort of collapsed working cycle, where data analysis parallels and informs collection rather than following it; and DADiSP arose from just such a need. [Read more]