The NETFLOW Procedure

PRINT Statement

Subsections:

Displaying Information On All Constraints
Displaying Information About Selected Arcs
Displaying Information About Selected Constraints
Cautions

PRINT options / qualifiers;

The options available with the PRINT statement of PROC NETFLOW are summarized by purpose in the following table.

Table 6.2: Functional Summary, PRINT Statement

Description	Statement	Option
PRINT Statement Options:
Display everything	PRINT	PROBLEM
Display arc information	PRINT	ARCS
Display nonarc variable information	PRINT	NONARCS
Display variable information	PRINT	VARIABLES
Display constraint information	PRINT	CONSTRAINTS
Display information for some arcs	PRINT	SOME_ARCS
Display information for some nonarc variables	PRINT	SOME_NONARCS
Display information for some variables	PRINT	SOME_VARIABLES
Display information for some constraints	PRINT	SOME_CONS
Display information for some constraints associated with some arcs	PRINT	CON_ARCS
Display information for some constraints associated with some nonarc variables	PRINT	CON_NONARCS
Display information for some constraints associated with some variables	PRINT	CON_VARIABLES
PRINT Statement Qualifiers:
Produce a short report	PRINT	/ SHORT
Produce a long report	PRINT	/ LONG
Display arcs/variables with zero flow/value	PRINT	/ ZERO
Display arcs/variables with nonzero flow/value	PRINT	/ NONZERO
Display basic arcs/variables	PRINT	/ BASIC
Display nonbasic arcs/variables	PRINT	/ NONBASIC

The PRINT statement enables you to examine part or all of the problem. You can limit the amount of information displayed when a PRINT statement is processed by specifying PRINT statement options. The name of the PRINT option indicates what part of the problem is to be examined. If no options are specified, or PRINT PROBLEM is specified, information about the entire problem is produced.

The amount of displayed information can be limited further by following any PRINT statement options with a slash (/) and one or more of the qualifiers SHORT or LONG, ZERO or NONZERO, BASIC or NONBASIC.

Some of the PRINT statement options require you to specify a list of some type of entity, thereby enabling you to indicate what entities are of interest. The entities of interest are the ones you want to display. These entities might be tail node names, head node names, nonarc variable names, or constraint names. The entity list is made up of one or more of the following constructs. Each construct can add none, one, or more entities to the set of entities to be displayed.

_ALL_ Display all entities in the required list.
entity Display the named entity that is interesting.
entity1 - entity2 (one hyphen) entity1 -- entity2 (two hyphens) entity1 - CHARACTER - entity2 or entity1 - CHAR - entity2 Both entity1 and entity2 have names made up of the same character string prefix followed by a numeric suffix. The suffixes of both entity1 and entity2 have the same number of numerals but can have different values. A specification of entity1 - entity2 indicates that all entities with the same prefix and suffixes with values on or between the suffixes of entity1 and entity2 are to be put in the set of entities to be displayed. The numeric suffix of both entity1 and entity2 can be followed by a character string. For example, _OBS07_ - _OBS13_ is a valid construct of the forms entity1 - entity2.
part_of_entity_name: Display all entities in the required list that have names beginning with the character string preceding the colon.

The following options can appear in the PRINT statement:

ARCS

indicates that you want to have displayed information about all arcs.

SOME_ARCS (taillist,headlist)

is similar to the statement PRINT ARCS except that, instead of displaying information about all arcs, only arcs directed from nodes in a specified set of tail nodes to nodes in a specified set of head nodes are included. The nodes or node constructs belonging to the taillist list are separated by blanks. The nodes or node constructs belonging to the headlist list are also separated by blanks. The lists are separated by a comma.

NONARCS VARIABLES

indicates that information is to be displayed about all nonarc variables.

SOME_NONARCS (nonarclist)

is similar to the PRINT NONARCS statement except that, instead of displaying information about all nonarc variables, only those belonging to a specified set of nonarc variables have information displayed. The nonarc variables or nonarc variable constructs belonging to the nonarclist list are separated by blanks.

CONSTRAINTS

indicates that you want to have displayed information about all constraint coefficients.

SOME_CONS (conlist)

displays information for coefficients in a specified set of constraints. The constraints or constraint constructs belonging to the conlist list are separated by blanks.

CON_ARCS (taillist, headlist)

is similar to the PRINT SOME_CONS (conlist) statement except that, instead of displaying information about all coefficients in specified constraints, information about only those coefficients that are associated with arcs directed from a set of specified tail nodes toward a set of specified head nodes is displayed. The constraints or constraint constructs belonging to the conlist list are separated by blanks; so too are the nodes or node constructs belonging to the taillist list and the nodes or node constructs belonging to the headlist list. The lists are separated by commas.

CON_NONARCS (conlist, nonarclist) CON_VARIABLES (conlist, variablelist)

is similar to the PRINT SOME_CONS (conlist) statement except that, instead of displaying information about all coefficients in specified constraints, information about only those coefficients that are associated with nonarc variables in a specified set is displayed. The constraints or constraint constructs belonging to the conlist list are separated by blanks. The nonarc variables or nonarc variable constructs belonging to the nonarclist list are separated by blanks. The lists are separated by a comma.

PROBLEM

is equivalent to the statement PRINT ARCS NONARCS CONSTRAINTS.

Following a slash (/), the qualifiers SHORT or LONG, ZERO or NONZERO, BASIC or NONBASIC can appear in any PRINT statement. These qualifiers are described below.

BASIC Only rows that are associated with arcs or nonarc variables that are basic are displayed. The _STATUS_ column values are KEY_ARC BASIC or NONKEY ARC BASIC for arcs, and NONKEY_BASIC for nonarc variables.
LONG All table columns are displayed (the default when no qualifier is used).
NONBASIC Only rows that are associated with arcs or nonarc variables that are nonbasic are displayed. The _STATUS_ column values are LOWERBD NONBASIC or UPPERBD NONBASIC.
NONZERO Only rows that have nonzero _FLOW_ column values (nonzero arc flows, nonzero nonarc variable values) are displayed.
SHORT The table columns are _N_, _FROM_, _TO_, _COST_, _CAPAC_, _LO_, _NAME_, and _FLOW_, or the names of the SAS variables specified in the corresponding variable lists (TAILNODE , HEADNODE , COST , CAPACITY , LO , and NAME lists). _COEF_ or the name of the SAS variable in the COEF list specification will head a column when the SHORT qualifier is used in PRINT CONSTRAINTS, SOME_CONS, CON_ARCS, or CON_NONARCS.
ZERO Only rows that have zero _FLOW_ column values (zero arc flows, zero nonarc variable values) are displayed.

The default qualifiers are BASIC, NONBASIC, ZERO, NONZERO, and LONG.

Displaying Information On All Constraints

In the oil refinery problem, if you had entered

   print constraints;

after the RUN statement, the output in Figure 6.9 would have been produced.

Displaying Information About Selected Arcs

In the oil refinery problem, if you had entered

   print some_arcs(refin:,_all_)/short;

after the RUN statement, the output in Figure 6.10 would have been produced.

Figure 6.9: PRINT CONSTRAINTS

Constrained Optimum

The NETFLOW Procedure

_N_	_CON_	_type_	_rhs_	_name_	_from_	_to_	_cost_	_capac_	_lo_	_SUPPLY_	_DEMAND_	_FLOW_	_COEF_	_FCOST_	_RCOST_	_STATUS_
1	_OBS1_	GE	-15	m_e_ref1	middle east	refinery 1	63	95	20	100	.	80	-2	5040	.	KEY_ARC BASIC
2	_OBS1_	GE	-15	thruput1	refinery 1	r1	200	175	50	.	.	145	1	29000	.	KEY_ARC BASIC
3	_OBS2_	GE	-15	m_e_ref2	middle east	refinery 2	81	80	10	100	.	20	-2	1620	.	NONKEY ARC BASIC
4	_OBS2_	GE	-15	thruput2	refinery 2	r2	220	100	35	.	.	35	1	7700	29	LOWERBD NONBASIC
5	_OBS3_	EQ	0	thruput1	refinery 1	r1	200	175	50	.	.	145	-3	29000	.	KEY_ARC BASIC
6	_OBS3_	EQ	0	r1_gas	r1	ref1 gas	0	140	0	.	.	108.75	4	0	.	KEY_ARC BASIC
7	_OBS4_	EQ	0	thruput2	refinery 2	r2	220	100	35	.	.	35	-3	7700	29	LOWERBD NONBASIC
8	_OBS4_	EQ	0	r2_gas	r2	ref2 gas	0	100	0	.	.	26.25	4	0	.	KEY_ARC BASIC

Figure 6.10: PRINT SOME_ARCS

Constrained Optimum

The NETFLOW Procedure

_N_	_from_	_to_	_cost_	_capac_	_lo_	_name_	_FLOW_
1	refinery 1	r1	200	175	50	thruput1	145
2	refinery 2	r2	220	100	35	thruput2	35

Displaying Information About Selected Constraints

In the oil refinery problem, if you had entered

  print some_cons(_obs3_-_obs4_)/nonzero short;

after the RUN statement, the output in Figure 6.11 would have been produced.

Figure 6.11: PRINT SOME_CONS

Constrained Optimum

The NETFLOW Procedure

_N_	_CON_	_type_	_name_	_from_	_to_	_cost_	_capac_	_lo_	_FLOW_	_COEF_
1	_OBS3_	EQ	thruput1	refinery 1	r1	200	175	50	145	-3
2	_OBS3_	EQ	r1_gas	r1	ref1 gas	0	140	0	108.75	4
3	_OBS4_	EQ	thruput2	refinery 2	r2	220	100	35	35	-3
4	_OBS4_	EQ	r2_gas	r2	ref2 gas	0	100	0	26.25	4

If you had entered

  print con_arcs(_all_,r1 r2,_all_)/short;

after the RUN statement, the output in Figure 6.12 would have been produced. Constraint information about arcs directed from selected tail nodes is displayed.

Figure 6.12: PRINT CON_ARCS

Constrained Optimum

The NETFLOW Procedure

_N_	_CON_	_type_	_rhs_	_name_	_from_	_to_	_cost_	_capac_	_lo_	_FLOW_	_COEF_
1	_OBS3_	EQ	0	r1_gas	r1	ref1 gas	0	140	0	108.75	4
2	_OBS4_	EQ	0	r2_gas	r2	ref2 gas	0	100	0	26.25	4

Cautions

This subsection has two parts; the first part is applicable if you are running Version 7 or later of the SAS System, and the second part is applicable if you are running Version 6. You can get later versions to "act" like Version 6 by specifying

  options validvarname=v6;

For Version 7 onward, PROC NETFLOW strictly respects case sensitivity. The PRINT statements of PROC NETFLOW that require lists of entities will work properly only if the entities have the same case as in the input data sets. Entities that contain blanks must be enclosed in single or double quotes. For example,

  print some_arcs (_all_,"Ref1 Gas");

In this example, a head node of an arc in the model is "Ref1 Gas" (without the quotes). If you omit the quotes, PROC NETFLOW issues a message on the SAS log:

  WARNING: The node Ref1 in the list of head nodes in the PRINT
           SOME_ARCS or PRINT CON_ARCS is not a node in the
           problem. This statement will be ignored.

If you had specified

  print some_arcs (_all_,"ref1 Gas");

(note the small r), you would have been warned

  WARNING: The node ref1 Gas in the list of head nodes in the PRINT
           SOME_ARCS or PRINT CON_ARCS is not a node in the
           problem. This statement will be ignored.

If you are running Version 6, or if you are running a later version and you have specified

  options validvarname=v6;

when information is parsed to procedures, the SAS System converts the text that makes up statements into uppercase. The PRINT statements of PROC NETFLOW that require lists of entities will work properly only if the entities are uppercase in the input data sets. If you do not want this uppercasing to occur, you must enclose the entity in single or double quotes.

  print some_arcs('lowercase tail','lowercase head');
  print some_cons('factory07'-'factory12');
  print some_cons('_factory07_'-'_factory12_');
  print some_nonarcs("CO2 content":);

Entities that contain blanks must be enclosed in single or double quotes.