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Modified _parse_gdx_results in GAMS.py to replace _parse_special_value and Updated Import Statement #3642

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Modified _parse_gdx_results in GAMS.py to replace _parse_special_value and Updated Import Statement #3642

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fdab163
Updated import statement from John's suggestion
Jun 23, 2025
1b74aff
Modified _parse_gdx_results to use GAMS interfaces instead of _parse_…
Jun 23, 2025
103f21c
Removed numpy dependency by using the equivalent sys.float_info.min. …
Jun 25, 2025
760b29b
Update GAMS.py - Typo in import statement
AnhTran01 Jun 25, 2025
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44 changes: 40 additions & 4 deletions pyomo/solvers/plugins/solvers/GAMS.py
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,23 @@
)

from pyomo.common.dependencies import attempt_import
import struct

gdxcc, gdxcc_available = attempt_import('gdxcc')
def _gams_importer():
try:
import gams.core.gdx as gdx
return gdx
except ImportError:
try:
# fall back to the pre-GAMS-45.0 API
import gdxcc
return gdxcc
except:
# suppress the error from the old API and reraise the current API import error
pass
raise

gdxcc, gdxcc_available = attempt_import('gdxcc', importer=_gams_importer)

logger = logging.getLogger('pyomo.solvers')

Expand Down Expand Up @@ -1277,6 +1292,16 @@ def _parse_gdx_results(self, results_filename, statresults_filename):
ret = gdxcc.gdxOpenRead(pgdx, statresults_filename)
if not ret[0]:
raise RuntimeError("GAMS GDX failure (gdxOpenRead): %d." % ret[1])

specVals = gdxcc.doubleArray(gdxcc.GMS_SVIDX_MAX)
rc = gdxcc.gdxGetSpecialValues(pgdx, specVals)

specVals[gdxcc.GMS_SVIDX_EPS] = sys.float_info.min
specVals[gdxcc.GMS_SVIDX_UNDEF] = float("nan")
specVals[gdxcc.GMS_SVIDX_PINF] = float("inf")
specVals[gdxcc.GMS_SVIDX_MINF] = float("-inf")
specVals[gdxcc.GMS_SVIDX_NA] = struct.unpack(">d", bytes.fromhex("fffffffffffffffe"))[0]
gdxcc.gdxSetSpecialValues(pgdx, specVals)

i = 0
while True:
Expand All @@ -1299,7 +1324,7 @@ def _parse_gdx_results(self, results_filename, statresults_filename):
raise RuntimeError("GAMS GDX failure (gdxDataReadRaw).")

if stat in ('OBJEST', 'OBJVAL', 'ETSOLVE'):
stat_vars[stat] = self._parse_special_values(ret[2][0])
stat_vars[stat] = ret[2][0]
else:
stat_vars[stat] = int(ret[2][0])

Expand All @@ -1311,6 +1336,16 @@ def _parse_gdx_results(self, results_filename, statresults_filename):
if not ret[0]:
raise RuntimeError("GAMS GDX failure (gdxOpenRead): %d." % ret[1])

specVals = gdxcc.doubleArray(gdxcc.GMS_SVIDX_MAX)
rc = gdxcc.gdxGetSpecialValues(pgdx, specVals)

specVals[gdxcc.GMS_SVIDX_EPS] = sys.float_info.min
specVals[gdxcc.GMS_SVIDX_UNDEF] = float("nan")
specVals[gdxcc.GMS_SVIDX_PINF] = float("inf")
specVals[gdxcc.GMS_SVIDX_MINF] = float("-inf")
specVals[gdxcc.GMS_SVIDX_NA] = struct.unpack(">d", bytes.fromhex("fffffffffffffffe"))[0]
gdxcc.gdxSetSpecialValues(pgdx, specVals)

i = 0
while True:
i += 1
Expand All @@ -1321,8 +1356,8 @@ def _parse_gdx_results(self, results_filename, statresults_filename):
ret = gdxcc.gdxDataReadRaw(pgdx)
if not ret[0] or len(ret[2]) < 2:
raise RuntimeError("GAMS GDX failure (gdxDataReadRaw).")
level = self._parse_special_values(ret[2][0])
dual = self._parse_special_values(ret[2][1])
level = ret[2][0]
dual = ret[2][1]

ret = gdxcc.gdxSymbolInfo(pgdx, i)
if not ret[0]:
Expand All @@ -1335,6 +1370,7 @@ def _parse_gdx_results(self, results_filename, statresults_filename):
gdxcc.gdxClose(pgdx)

gdxcc.gdxFree(pgdx)
gdxcc.gdxLibraryUnload()
return model_soln, stat_vars

def _parse_dat_results(self, results_filename, statresults_filename):
Expand Down