Operators and functions

Operators and functions are used in expressions to calculate with data items and or literals.

operators

An operator is a symbolic presentation of a function to be applied on operands.

functions

Functions express dependences between items. A function associates a single output to each input element. Functions in the GeoDMS are categorized in the following function groups:

• Arithmetic: basic mathematical functions, like add, divide or sqrt
• Ordering: to compare/order data items like eq, less than, argmax or sort
• Aggregation: to aggregate data items to other domain units like sum or mean
• Conversion: to convert value types, round data items or use different notations
• Classify: to classify quantities to class units
• Transcendental: functions transcending algebra, like exponent and logarithm
• Predicates: to check conditions, like isdefined of isnull.
• Logical: to provide basic comparisons, returning in boolean data items like iif or and
• Relational: to relate data items of different domain units like lookup or create new domain units like unique
• Selection: to create new domain units for selections of data from other domain units like select_with_attr_by_cond
• Rescale: to scale data items to new distributions
• Constant: to define constant values like pi or true
• Trigonometric: operate on angles like sine or cosine.
• Geometric: geometric operations on points, arcs and/or polygons
• Network: to build and calculate network topologies like connect or impedance
• Grid: to calculate with data items of grid (two-dimensional) domains, like potential or district
• String: operate on data items with string value types like left or strcount
• File, Folder and Read: operate on files and folders, like makedir or storage_name
• Unit: to define and get information of unit items, like rangeand lowerbound
• Matrix: to perform matrix calculations, like matrix-multiplication or matrix-inverse
• Sequence: process data items with one-dimensional sequences.
• MetaScript:to generate script (like for_each) or request information on tree items like subitem_propvalues
• Allocation: mainly used for Land Use Allocation
• Miscellaneous: remaining functions not categorized in other groups, like rnd_uniform or propvalue