Determining the arguments of a functional map

The input arguments of a functional map are the objects necessary to create one occurrence of the output object where the map rule is.

To determine what the input argument(s) of a functional map should be, ask yourself, "What do I need to create this output?" Whatever is necessary in a functional map must be passed to it as an argument. There may be one or more input arguments. The arguments of a functional map can be thought of as triggers. The number of times a functional map is triggered depends on the number of occurrences of the input arguments in the data and the expressions used for each argument.

To determine the input arguments of a functional map, ask yourself what objects are necessary to create one occurrence of the output object.