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Mosel files for the Mosel-Python comparison blog Description Mosel files for the blog post comparing Mosel and Python. Instructions for running these files:
Source Files By clicking on a file name, a preview is opened at the bottom of this page. Data Files TSP_adv.mos
(!******************************************************
Mosel Example Problems
======================
file TSP_adv.mos
````````````````
Improved version of model 'TSP_std.mos'.
-- Advanced optimization tasks (solution loading, callbacks, cuts) --
(c) 2019-2025 Fair Isaac Corporation
author: S.Heipcke
*******************************************************!)
model "TSP test"
uses "mmxprs", "mmsystem", "mmsheet", "mmetc"
parameters
DATA_FILE_PREFIX = "00"
TOL=10E-10
end-parameters
writeln("#E:IMPORT")
forward procedure printsol
forward procedure cb_preintsol(isheur: boolean, cutoff: real)
forward function cb_optnode: boolean
writeln("#S:READ")
declarations
CITIES: range ! Set of cities
X,Y: array(CITIES) of real
ONETOL = 1-TOL ! Constant to replace repeated calculations
end-declarations
initializations from "mmetc.diskdata:"
[X, Y] as "csv,skiph," + DATA_FILE_PREFIX + "_H_TSP_cities.csv"
end-initializations
declarations
NCITIES=getsize(CITIES)
DIST: array(CITIES,CITIES) of integer ! Distance between cities
NEXTC: array(CITIES) of integer ! Next city after i in the solution
fly: array(CITIES,CITIES) of mpvar ! 1 iff flight from i to j
INITTOURS = 1..10
InitTours : array(INITTOURS) of mpsol
end-declarations
declarations
CITYORDER = 1..NCITIES + 1
TOURS: array(INITTOURS, CITYORDER) of integer
end-declarations
diskdata(ETC_DENSE, DATA_FILE_PREFIX + "_H_TSP_tours.csv", TOURS)
writeln("#E:READ")
writeln("#S:PROC")
forall(t in INITTOURS,i in CITIES)
setsol(InitTours(t),fly(TOURS(t, i),TOURS(t, i + 1)),1)
forall(i,j in CITIES | i<>j)
DIST(i,j):=ceil(sqrt((X(i)-X(j))^2 + (Y(i)-Y(j))^2))
! Objective: total distance
TotalDist:= sum(i,j in CITIES | i<>j) DIST(i,j)*fly(i,j)
! Visit every city once
forall(i in CITIES) sum(j in CITIES | i<>j) fly(i,j) = 1
forall(j in CITIES) sum(i in CITIES | i<>j) fly(i,j) = 1
forall(i,j in CITIES | i<>j) fly(i,j) is_binary
! Set a callback to check heuristic solutions
setcallback(XPRS_CB_PREINTSOL, ->cb_preintsol)
! Set a callback to create subtour elimination constraints for integer solutions
setcallback(XPRS_CB_OPTNODE, ->cb_optnode)
! Disable symmetry detection
setparam("XPRS_SYMMETRY", 0)
setparam("XPRS_VERBOSE", false)
setparam("XPRS_TIMELIMIT", 100) ! set a time limit
loadprob(TotalDist)
forall(t in INITTOURS)
addmipsol("InitTour_" + t, InitTours(t))
minimize(TotalDist)
assert(getparam("XPRS_MIPSOLS") > 0)
writeln("#E:PROC")
writeln("#S:TEST")
printsol
writeln("#E:TEST")
!-----------------------------------------------------------------
! Callback function triggered when the Optimizer has a new integer
! solution
!
! We use this function to reject any heuristic solutions that
! contain subtours.
procedure cb_preintsol(isheur: boolean, cutoff: real)
declarations
iCity: integer
nCitiesVisited: integer
end-declarations
! Get the tour(s)
forall(i in CITIES)
forall(j in CITIES)
if (getsol(fly(i,j))>=ONETOL) then
NEXTC(i):=j
break
end-if
! Verify that we have a complete tour
nCitiesVisited := 1;
iCity := 1
while (NEXTC(iCity) <> 1) do
iCity := NEXTC(iCity)
nCitiesVisited += 1
end-do
if (nCitiesVisited < NCITIES) then
if isheur then
rejectintsol
else
writeln("INVALID INTEGER SOLUTION!!!")
end-if
end-if
end-procedure
!-----------------------------------------------------------------
! Callback function triggered when a node relaxation has been
! solved to optimality and the Optimizer is about to branch or
! declare the node integer feasible.
!
! If the node is about to be declared integer feasible, we need
! to check for subtours and add at least one violated subtour
! elimination constraint.
function cb_optnode: boolean
declarations
SUBTOUR: set of integer
VISITEDCITIES: set of integer
iCity: integer
MipInfeas: integer
ncut:integer
CutRange: range ! Counter for cuts
cut: array(CutRange) of linctr ! Cuts
cutid: array(CutRange) of integer ! Cut type identification
type: array(CutRange) of integer ! Cut constraint type
end-declarations
returned:=false ! Call this function once per node
MipInfeas := getparam("XPRS_MIPINFEAS");
if (MipInfeas = 0) then
! There are no fractionals left in the current node solution.
! Create sub-tour elimination constraints if we do not
! have a complete tour.
ncut:= 0
forall(i in CITIES)
forall(j in CITIES)
if(getsol(fly(i,j))>=ONETOL) then
NEXTC(i):=j
break
end-if
VISITEDCITIES := {}
forall (iFirstCity in CITIES)
if not iFirstCity in VISITEDCITIES then
SUBTOUR := {}
iCity := iFirstCity
while (iCity not in SUBTOUR) do
SUBTOUR += {iCity}
iCity := NEXTC(iCity)
end-do
if (getsize(SUBTOUR) < NCITIES) then
! Create the sub-tour elimination cut(s)
cutid(ncut):= 0
type(ncut):= CT_LEQ
cut(ncut):= sum(i in SUBTOUR) fly(i,NEXTC(i)) - (getsize(SUBTOUR) - 1)
ncut+=1
! Optional: Also exclude the inverse subtour
cutid(ncut):= 0
type(ncut):= CT_LEQ
cut(ncut):= sum(i in SUBTOUR) fly(NEXTC(i),i) - (getsize(SUBTOUR) - 1)
ncut+=1!)
! Optional: Add a stronger subtour elimination cut
cutid(ncut):= 0
type(ncut):= CT_GEQ
cut(ncut) := sum(i in SUBTOUR, j in (CITIES)-SUBTOUR) fly(i,j) - 1
ncut+=1!)
end-if
VISITEDCITIES += SUBTOUR
end-if
! Add cuts to the problem
if(ncut>0) then
addcuts(cutid, type, cut);
num_cuts_added+=ncut
end-if
end-if ! MIPINFEAS
end-function
!-----------------------------------------------------------------
! Print the current solution
procedure printsol
declarations
ALLCITIES: set of integer
CalcDistance: real
end-declarations
! Get the final tour
forall(i in CITIES)
forall(j in CITIES)
if (getsol(fly(i,j))>=ONETOL) then
NEXTC(i):=j
break
end-if
! Recalculate the length of the tour
CalcDistance := sum(i in 1..NCITIES) DIST(i, NEXTC(i))
writeln("Total distance: ", CalcDistance)
ALLCITIES:={}
forall(i in CITIES) do
if (i not in ALLCITIES) then
write(i)
first:=i
repeat
ALLCITIES+={first}
write(" - ", NEXTC(first))
first:=NEXTC(first)
until first=i
writeln
end-if
end-do
end-procedure
!-----------------------------------------------------------------
end-model
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| © Copyright 2025 Fair Isaac Corporation. |
