How to store the zero elements in a solution?

GAMSPy
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1

When exporting solutions to pandas df and excel out of GAMSPy the zeros are stripped out.

Similar to:
(How to store the zero elements in a solution? - #2 by Archiver)

is there a way to force write all zeros when reporting solution values?
2

Zeros are stripped out automatically for performance reasons. If you want to restore them, you can assign EPS to the unset elements of the solution. For example:

from gamspy import Container, Set, Parameter, SpecialValues

m = Container()

i = Set(m, "i", records=['i1', 'i2'])
a = Parameter(m, "a", domain=i, records=[('i1', 1)])
print(a.records)

a[i].where[~a[i]] = SpecialValues.EPS
print(a.records)

This would print:

    i  value
0  i1    1.0
    i  value
0  i1    1.0
1  i2   -0.0

As you can see from the output, EPS values are stored as -0.0 in the DataFrame. You can now export the DataFrame to a csv file with the zeros in it:

a.records.to_csv("out.csv")

If you want to export them to a gdx file, make sure to set the eps_to_zero flag to False:

m.write("out.gdx", eps_to_zero=False)

gdxdump on the generated gdx file should show:

Set i(*) /
'i1', 
'i2' /;

Parameter a(i) /
'i1' 1, 
'i2' Eps /;
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