Appendix VI

Parameter File Specification

Introduction:

The parameter file format is a general purpose format created to facilitate the use of simple text files for specifying large numbers of parameters to a variety of different programs. This document will describe the format along with the data types that it supports and the syntax that it requires.

Parameter files may be used by anyone who writing a program that requires user-specified values that may change each time the program is run. The format supports the specification of integer, floating-point, character, and list parameters. List parameters are used for grouping together an arbitrary number of parameters under a common label. Figure 5.1 illustrates a portion of a PHG run-time parameter file.

 

REAL photon_energy = 511.0

REAL weight_window_ratio = 3.0

BOOL point_source_voxels = false

INT random_seed = 442598

 

# OBJECT GEOMETRY VALUES

NUM_ELEMS_IN_LIST object = 2

INT num_slices = 1

NUM_ELEMS_IN_LIST slice = 9

INT slice_number = 0

REAL zMin = -50.00

 

REAL zMax = 0.00

REAL xMin = -5.00

REAL xMax = 5.00

REAL yMin = -5.00

REAL yMax = 5.00

INT num_x_bins = 1

INT num_y_bins = 1

# PHOTON HISTORY FILE

STRING "history.file"

Figure A6.1

Parameter specifications consist of a type, label, and value. In the first line of figure 5.1 the parameter type is REAL (corresponding to floating point), the label is photon_energy, and the value is 511.0.

White space is ignored. Everything following the last non white-space character of the value is ignored as well (so you can put comments at the end of a parameter line). For STRING parameters the value is delimited with double quotation marks.

Lines that begin with the '#' character are considered comments and are ignored. Blank lines are also ignored. Any line that does not have a '#' character as the first non white-space character must begin with one of the following:

• BOOL: Indicates boolean parameter, value must be 'TRUE' or 'FALSE'. Note that values are case insensitive.
• INT: Indicates integer parameter, value must be 32 bit integer value.
• REAL: Indicates 64 bit floating point value.
• STRING: Indicates character string parameter, value must fit on a single line and be delimeted with double quote marks. There is no support for embeding double quotes within the string.
• NUM_ELEMENTS_IN_LIST: Indicates a list parameter, the value specifies the number of elements in the list. Lists may be embedded within lists, in which case they represent a single element. Figure A6.1 illustrates this use: the first list (label is "object") contains two elements, the first is "num_slices" and the second is a list representing a slice.

For further information on parameter files, including information on how to create your own, refer to the Parameter File section of the Programmer's Manual for the PHG.