How to Manipulate Prj-Files

Section author: Jörg Buchwald (Helmholtz Centre for Environmental Research GmbH - UFZ)

E.g., to iterate over three Young’s moduli one can use the replace parameter method.

Initialize the ogs6py object:

import ogstools as ogs
from ogstools.definitions import EXAMPLES_DIR

youngs_moduli = [1, 2, 3]
filename = EXAMPLES_DIR / "prj/simple_mechanics.prj"
for youngs_modulus in youngs_moduli:
    prj = ogs.Project(input_file=filename, output_file=filename)
    prj.replace_parameter_value(name="E", value=youngs_modulus)
    prj.replace_text(
        f"out_E={youngs_modulus}", xpath="./time_loop/output/prefix"
    )
    prj.write_input()
    prj.run_model()

OGS finished with project file /builds/ogs/tools/ogstools/ogstools/examples/prj/simple_mechanics.prj.
Execution took 0.1439681053161621 s
Project file written to output.
OGS finished with project file /builds/ogs/tools/ogstools/ogstools/examples/prj/simple_mechanics.prj.
Execution took 0.137037992477417 s
Project file written to output.
OGS finished with project file /builds/ogs/tools/ogstools/ogstools/examples/prj/simple_mechanics.prj.
Execution took 0.12740135192871094 s
Project file written to output.

Instead of the replace_parameter method, the more general replace_text method can also be used to replace the young modulus in this example:

prj.replace_text(youngs_modulus, xpath="./parameters/parameter[name='E']/value")

The Young’s modulus in this file can also be accessed through 0’th occurrence of the place addressed by the xpath

prj.replace_text(
    youngs_modulus, xpath="./parameters/parameter/value", occurrence=0
)

The density can also be changed:

prj.replace_phase_property_value(
    mediumid=0, phase="Solid", name="density", value="42"
)

For MPL (Material Property Library) based processes, like TH2M or Thermo-Richards-Mechanics, there exist specific functions to set phase and medium properties: e.g.:, model.replace_medium_property_value(mediumid=0, name=”porosity”, value=”0.24”)