A lookup table is a function, mapping input values to output values. The command lut creates an object representing
a lookup table, which can then be used to control various behaviour
in the spatstat package. It can also be used to compute the
output value assigned to any input value.
The argument outputs specifies the output values to which
input data values will be mapped. It should be a vector of
any atomic type (e.g. numeric, logical, character, complex) or factor
values.
Exactly one of the arguments inputs and breaks
must be specified by name.
If inputs is given, then it should be a vector or factor,
of the same length as outputs. The entries of inputs can be
any atomic type (e.g. numeric, logical, character, complex) or factor
values. The resulting lookup table associates the value inputs[i]
with the value outputs[i].
If breaks is given, then it determines intervals
of the real number line
which are mapped to each output value. It should be a numeric vector,
of length at least 2, with entries that are in increasing order.
Infinite values are allowed. Any number in the range
between breaks[i] and breaks[i+1] will be mapped to the
value outputs[i].
The result is an object of class "lut".
There is a print method for this class.
Some plot commands in the spatstat package accept an object
of this class as a specification of a lookup table.
The result is also a function f which can be used to compute
the output value assigned to any input data value.
That is, f(x) returns the output value assigned
to x. This also works for vectors of input data values.