Functions
def	get_model_text ()

Variables
	ws = GamsWorkspace(system_directory = sys.argv[1])

int	cuts_per_round = 10

int	curcut = 0

int	cmax = 0

	cut_data = ws.add_database()

	cc = cut_data.add_set("cc", 1, "")

	acut = cut_data.add_parameter("acut", 3, "")

	rhscut = cut_data.add_parameter("rhscut", 1, "")

list	n = []

	tsp_job = ws.add_job_from_string(get_model_text())

	cp = ws.add_checkpoint()

	opt = ws.add_options()

	gams_options

	checkpoint

	mi = cp.add_modelinstance()

	mi_acut = mi.sync_db.add_parameter("acut", 3, "")

	mi_rhscut = mi.sync_db.add_parameter("rhscut", 1, "")

dictionary	graph = {}

	not_visited = list(n)

	i = not_visited[0]

list	sub_tour = [i]

	value

	end

Function Documentation

◆ get_model_text()

def tsp.get_model_text ( )

Definition at line 18 of file tsp.py.

def get_model_text():
     return '''
 $Title Traveling Salesman Problem Instance with Python
  
 $Ontext
  
 The sub_tour elimination constraints are generated by a Python
 script. The MIP is solved over and over, but GAMS have to
 generate the model only after n cuts have been added.
  
 $Offtext
  
 $if not set tspdata $abort 'tspdata not set'
  
 set ii    cities
     i(ii) subset of cities
 alias (ii,jj),(i,j,k);
  
 parameter c(ii,jj) distance matrix;
  
 $gdxin %tspdata%
 $load ii c
  
 $if not set nrCities $set nrCities 20
 i(ii)$(ord(ii) < %nrCities%) = yes;
  
 variables x(ii,jj)  decision variables - leg of trip
           z         objective variable;
 binary variable x; x.fx(ii,ii) = 0;
  
 equations objective   total cost
           rowsum(ii)  leave each city only once
           colsum(jj)  arrive at each city only once;
  
 * the assignment problem is a relaxation of the TSP
 objective.. z =e= sum((i,j), c(i,j)*x(i,j));
 rowsum(i).. sum(j, x(i,j)) =e= 1;
 colsum(j).. sum(i, x(i,j)) =e= 1;
  
 $if not set cmax $set cmax 2
 set cut /c0*c%cmax%/;
 parameter
     acut(cut,ii,jj) cut constraint matrix
     rhscut(cut)  cut constraint rhs;
  
 equation sscut(cut) sub_tour elimination cut;
 sscut(cut).. sum((i,j), Acut(cut,i,j)*x(i,j)) =l= RHScut(cut);
  
 set cc(cut) previous cuts; cc(cut) = no;
 $if set cutdata execute_load '%cutdata%', cc, Acut, RHScut;
  
 Acut(cut,i,j)$(not cc(cut)) = eps;
 RHScut(cut)$(not cc(cut)) = card(ii);
  
 model assign /all/;
  
 option optcr=0; '''
  
  

Variable Documentation

◆ acut

tsp.acut = cut_data.add_parameter("acut", 3, "")

Definition at line 93 of file tsp.py.

◆ cc

tsp.cc = cut_data.add_set("cc", 1, "")

Definition at line 92 of file tsp.py.

◆ checkpoint

tsp.checkpoint

Definition at line 113 of file tsp.py.

◆ cmax

int tsp.cmax = 0

Definition at line 88 of file tsp.py.

◆ cp

tsp.cp = ws.add_checkpoint()

Definition at line 107 of file tsp.py.

◆ curcut

int tsp.curcut = 0

Definition at line 86 of file tsp.py.

◆ cut_data

tsp.cut_data = ws.add_database()

Definition at line 91 of file tsp.py.

◆ cuts_per_round

int tsp.cuts_per_round = 10

Definition at line 84 of file tsp.py.

◆ end

tsp.end

Definition at line 161 of file tsp.py.

◆ gams_options

tsp.gams_options

Definition at line 113 of file tsp.py.

◆ graph

dictionary tsp.graph = {}

Definition at line 132 of file tsp.py.

◆ i

dictionary tsp.i = not_visited[0]

Definition at line 140 of file tsp.py.

◆ mi

tsp.mi = cp.add_modelinstance()

Definition at line 121 of file tsp.py.

◆ mi_acut

tsp.mi_acut = mi.sync_db.add_parameter("acut", 3, "")

Definition at line 122 of file tsp.py.

◆ mi_rhscut

tsp.mi_rhscut = mi.sync_db.add_parameter("rhscut", 1, "")

Definition at line 123 of file tsp.py.

◆ n

list tsp.n = []

Definition at line 96 of file tsp.py.

◆ not_visited

tsp.not_visited = list(n)

Definition at line 133 of file tsp.py.

◆ opt

tsp.opt = ws.add_options()

Definition at line 108 of file tsp.py.

◆ rhscut

tsp.rhscut = cut_data.add_parameter("rhscut", 1, "")

Definition at line 94 of file tsp.py.

◆ sub_tour

list tsp.sub_tour = [i]

Definition at line 141 of file tsp.py.

◆ tsp_job

tsp.tsp_job = ws.add_job_from_string(get_model_text())

Definition at line 106 of file tsp.py.

◆ value

tsp.value

Definition at line 149 of file tsp.py.

◆ ws

tsp.ws = GamsWorkspace(system_directory = sys.argv[1])

Definition at line 79 of file tsp.py.

Functions

Variables