Re: Help: Switch constraints on or off
On 11/24/20 10:12 PM, Greg Gruber wrote:
Hi Manuel,
try setting StorageFlag to 1 or 0 as a parameter (based on your data),
and then doing this:
subject to linctr14-1 {i in PeriodsCount: i == 1}:
StorageEnergy[i] >= StorageFlag*( existing constraint ) ;
subject to linctr14-0 {i in PeriodsCount: i == 1}:
StorageEnergy[i] <= StorageFlag*( existing constraint ) +
(1-StorageFlag) * M ;
When StorageFlag = 1, these two constraints equate to your equality
constraint.
When StorageFlag = 0, the constraints just become bounds (0 and M). If
you want to allow StorageEnergy[i] to be negative, you could add " -
(1-StorageFlag)*M" to the first constraint.
This approach is adequate if StorageFlag is a binary *variable*. For a
*parameter* selecting constraints see
https://en.wikibooks.org/wiki/GLPK/Conditional_Constraints.
Best regards
Heinrich
I *think* this will work -- good luck!
Best regards,
Greg
-
Message: 1
Date: Tue, 24 Nov 2020 18:59:09 +
From: Manuel Castro mailto:m.j.cas...@zoho.com>>
To: "help-glpk" mailto:help-glpk@gnu.org>>
Subject: Help: Switch constraints on or off
Message-ID: <175fb9fb6e3.12bae7aa873758.2962621200961588...@zoho.com
>
Content-Type: text/plain; charset="utf-8"
Hi there,
I am wondering how I can use an if statement to turn a constraint on
or off.
For example in my problem I have the following constraint:
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
(StorageStateCharge * StorageEnergyRating +
((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
Now, I only want to consider storage in my problem if an object
storage actually exists.
For that, I would have a StorageStatusFlag which if equal to "1"
then I would consider the constraint in my problem.
For example:
If (StorageStatusFlag == 1) then
subject to linctr14 {i in PeriodsCount: i == 1}:
StorageEnergy[i] = (StorageStateCharge * StorageEnergyRating +
((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
end if
This is what I used to do in "mosel" language from FICO Xpress (I
don't have a license anymore so I am discovering GLPK ). How can I
do this in GLPK language? What's the workaround that we can use for
this?
Many thanks in advance for your help. It's really appreciated.
Kind regards,
Manuel.
Re: Help: Switch constraints on or off
Hi Manuel,
try setting StorageFlag to 1 or 0 as a parameter (based on your data), and
then doing this:
subject to linctr14-1 {i in PeriodsCount: i == 1}:
StorageEnergy[i] >= StorageFlag*( existing constraint ) ;
subject to linctr14-0 {i in PeriodsCount: i == 1}:
StorageEnergy[i] <= StorageFlag*( existing constraint ) +
(1-StorageFlag) * M ;
When StorageFlag = 1, these two constraints equate to your equality
constraint.
When StorageFlag = 0, the constraints just become bounds (0 and M). If you
want to allow StorageEnergy[i] to be negative, you could add " -
(1-StorageFlag)*M" to the first constraint.
I *think* this will work -- good luck!
Best regards,
Greg
> -
>
> Message: 1
> Date: Tue, 24 Nov 2020 18:59:09 +
> From: Manuel Castro
> To: "help-glpk"
> Subject: Help: Switch constraints on or off
> Message-ID: <175fb9fb6e3.12bae7aa873758.2962621200961588...@zoho.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi there,
>
>
>
> I am wondering how I can use an if statement to turn a constraint on or
> off.
>
> For example in my problem I have the following constraint:
>
>
>
> subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
> (StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge *
> (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
> StorageEfficiencyDischarge)));
>
>
>
> Now, I only want to consider storage in my problem if an object storage
> actually exists.
>
> For that, I would have a StorageStatusFlag which if equal to "1" then I
> would consider the constraint in my problem.
>
> For example:
>
>
>
> If (StorageStatusFlag == 1) then
>
> subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
> (StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge *
> (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
> StorageEfficiencyDischarge)));
>
> end if
>
>
> This is what I used to do in "mosel" language from FICO Xpress (I don't
> have a license anymore so I am discovering GLPK ). How can I do this in
> GLPK language? What's the workaround that we can use for this?
>
>
>
> Many thanks in advance for your help. It's really appreciated.
>
>
>
> Kind regards,
>
> Manuel.
>
>
Re: Help: Switch constraints on or off
On 11/24/20 9:30 PM, Heinrich Schuchardt wrote:
On 11/24/20 8:42 PM, Andrew Makhorin wrote:
On Tue, 2020-11-24 at 18:59 +, Manuel Castro wrote:
Hi there,
I am wondering how I can use an if statement to turn a constraint on
or off.
For example in my problem I have the following constraint:
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
(StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge
* (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
StorageEfficiencyDischarge)));
Now, I only want to consider storage in my problem if an object
storage actually exists.
For that, I would have a StorageStatusFlag which if equal to "1" then
I would consider the constraint in my problem.
For example:
If (StorageStatusFlag == 1) then
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i]
= (StorageStateCharge * StorageEnergyRating +
((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
end if
Just add the condition to the constraint iterator:
subject to
linctr14{i in PeriodsCount: i == 1 && StorageStatusFlag == 1}:
I have updated our wikibook
https://en.wikibooks.org/wiki/GLPK/Conditional_Constraints
Best regards
Heinrich
This is what I used to do in "mosel" language from FICO Xpress (I
don't have a license anymore so I am discovering GLPK ). How can I do
this in GLPK language? What's the workaround that we can use for this?
You could use the C preprocessor.
Many thanks in advance for your help. It's really appreciated.
Kind regards,
Manuel.
Re: Help: Switch constraints on or off
On 11/24/20 8:42 PM, Andrew Makhorin wrote:
On Tue, 2020-11-24 at 18:59 +, Manuel Castro wrote:
Hi there,
I am wondering how I can use an if statement to turn a constraint on
or off.
For example in my problem I have the following constraint:
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
(StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge
* (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
StorageEfficiencyDischarge)));
Now, I only want to consider storage in my problem if an object
storage actually exists.
For that, I would have a StorageStatusFlag which if equal to "1" then
I would consider the constraint in my problem.
For example:
If (StorageStatusFlag == 1) then
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i]
= (StorageStateCharge * StorageEnergyRating +
((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
end if
Just add the condition to the constraint iterator:
subject to
linctr14{i in PeriodsCount: i == 1 && StorageStatusFlag == 1}:
Best regards
Heinrich
This is what I used to do in "mosel" language from FICO Xpress (I
don't have a license anymore so I am discovering GLPK ). How can I do
this in GLPK language? What's the workaround that we can use for this?
You could use the C preprocessor.
Many thanks in advance for your help. It's really appreciated.
Kind regards,
Manuel.
Re: Help: Switch constraints on or off
Hi Andrew,Thank you for the prompt reply.What do you mean by C
prepocessor?? Apologies, I know how to program but that’s pretty much it...
On Tue, 24 Nov 2020 19:42:10 + m...@gnu.org wrote On
Tue, 2020-11-24 at 18:59 +, Manuel Castro wrote: > Hi there, > > I am
wondering how I can use an if statement to turn a constraint on > or off. > For
example in my problem I have the following constraint: > > subject to linctr14
{i in PeriodsCount: i == 1}: StorageEnergy[i] = > (StorageStateCharge *
StorageEnergyRating + ((StorageEfficiencyCharge > * (StoragePowerCharge[i])) -
((StoragePowerDischarge[i]) / > StorageEfficiencyDischarge))); > > Now, I only
want to consider storage in my problem if an object > storage actually exists.
> For that, I would have a StorageStatusFlag which if equal to "1" then > I
would consider the constraint in my problem. > For example: > > If
(StorageStatusFlag == 1) then > subject to linctr14 {i in PeriodsCount: i
== 1}: StorageEnergy[i] > = (StorageStateCharge * StorageEnergyRating + >
((StorageEfficiencyCharge * (StoragePowerCharge[i])) - >
((StoragePowerDischarge[i]) / StorageEfficiencyDischarge))); > end if > > This
is what I used to do in "mosel" language from FICO Xpress (I > don't have a
license anymore so I am discovering GLPK ). How can I do > this in GLPK
language? What's the workaround that we can use for this? You could use the C
preprocessor. > > Many thanks in advance for your help. It's really
appreciated. > > Kind regards, > Manuel. >
Re: Help: Switch constraints on or off
On Tue, 2020-11-24 at 18:59 +, Manuel Castro wrote:
> Hi there,
>
> I am wondering how I can use an if statement to turn a constraint on
> or off.
> For example in my problem I have the following constraint:
>
> subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
> (StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge
> * (StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
> StorageEfficiencyDischarge)));
>
> Now, I only want to consider storage in my problem if an object
> storage actually exists.
> For that, I would have a StorageStatusFlag which if equal to "1" then
> I would consider the constraint in my problem.
> For example:
>
> If (StorageStatusFlag == 1) then
> subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i]
> = (StorageStateCharge * StorageEnergyRating +
> ((StorageEfficiencyCharge * (StoragePowerCharge[i])) -
> ((StoragePowerDischarge[i]) / StorageEfficiencyDischarge)));
> end if
>
> This is what I used to do in "mosel" language from FICO Xpress (I
> don't have a license anymore so I am discovering GLPK ). How can I do
> this in GLPK language? What's the workaround that we can use for this?
You could use the C preprocessor.
>
> Many thanks in advance for your help. It's really appreciated.
>
> Kind regards,
> Manuel.
>
Re: Change Path Input/Output file
On Tue, 2020-11-24 at 19:11 +, Manuel Castro wrote: > Hi there, > > I am currently using gusek as an IDE to model and run GLPK. > I use the following statement to read from CSV file. > > table tab_plant IN "CSV" "plants.csv" : I <- [plant], a ~ capacity; > > This assumes that the file is placed in the same directory where the > glpk solver is. > How can I place my CSV file in a different directory and tell glpk to > read it from there? How do I add the path on my model syntax? Conventions are the same as in C programs. You can write "../foo/plants.csv" or MYDIR & "/plants.csv" where MYDIR is a symbolic parameter declared like this: param MYDIR, symbolic, := "../foo" > > Many thanks in advance for your help. It's really appreciated. > > Kind regards, > Manuel. >
Change Path Input/Output file
Hi there, I am currently using gusek as an IDE to model and run GLPK. I use the following statement to read from CSV file. table tab_plant IN "CSV" "plants.csv" : I <- [plant], a ~ capacity; This assumes that the file is placed in the same directory where the glpk solver is. How can I place my CSV file in a different directory and tell glpk to read it from there? How do I add the path on my model syntax? Many thanks in advance for your help. It's really appreciated. Kind regards, Manuel.
Help: Switch constraints on or off
Hi there,
I am wondering how I can use an if statement to turn a constraint on or off.
For example in my problem I have the following constraint:
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
(StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge *
(StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
StorageEfficiencyDischarge)));
Now, I only want to consider storage in my problem if an object storage
actually exists.
For that, I would have a StorageStatusFlag which if equal to "1" then I would
consider the constraint in my problem.
For example:
If (StorageStatusFlag == 1) then
subject to linctr14 {i in PeriodsCount: i == 1}: StorageEnergy[i] =
(StorageStateCharge * StorageEnergyRating + ((StorageEfficiencyCharge *
(StoragePowerCharge[i])) - ((StoragePowerDischarge[i]) /
StorageEfficiencyDischarge)));
end if
This is what I used to do in "mosel" language from FICO Xpress (I don't have a
license anymore so I am discovering GLPK ). How can I do this in GLPK language?
What's the workaround that we can use for this?
Many thanks in advance for your help. It's really appreciated.
Kind regards,
Manuel.
