Introduction
Comb merges multiple expressions in to one. All input expressions must have the same number of entities.
Example:
For example, let the list_of_expression contain the following expressions:
exp_list[0] = data{1, 2, 3} with 3 items, and item shape = []
- - -
exp_list[1] = data{4, 5, -1, 6, 7, -1, 8, 9, -1} with 3 items, and item shape = [3]
-------- -------- --------
The resulting expression has item shape [3] with 4 items:
output_exp = [1, 4, 5, -1, 2, 6, 7, -1, 3, 8, 9, -1]
--------- -------- --------
The expression won’t be evaluated unless Expression::Evaluate is called.
Use case
import KratosMultiphysics as Kratos
model = Kratos.Model()
model_part = model.CreateModelPart("test")
node_1 = model_part.CreateNewNode(1, 0, 0, 0)
node_2 = model_part.CreateNewNode(2, 1, 0, 0)
node_3 = model_part.CreateNewNode(3, 1, 1, 0)
# setting VELOCITY and PRESSURE of each node
node_1.SetValue(Kratos.VELOCITY, Kratos.Array3([4,5,-1]))
node_2.SetValue(Kratos.VELOCITY, Kratos.Array3([6,7,-1]))
node_3.SetValue(Kratos.VELOCITY, Kratos.Array3([8,9,-1]))
node_1.SetValue(Kratos.PRESSURE, 1)
node_2.SetValue(Kratos.PRESSURE, 2)
node_3.SetValue(Kratos.PRESSURE, 3)
# create expressions
u_exp = Kratos.Expression.NodalExpression(model_part)
p_exp = Kratos.Expression.NodalExpression(model_part)
# read data in to expressions
Kratos.Expression.VariableExpressionIO.Read(u_exp, Kratos.VELOCITY, False)
Kratos.Expression.VariableExpressionIO.Read(p_exp, Kratos.PRESSURE, False)
# now combine
combined_exp = Kratos.Expression.Utils.Comb([p_exp, u_exp])
print(combined_exp.Evaluate())
Expected output:
| / |
' / __| _` | __| _ \ __|
. \ | ( | | ( |\__ \
_|\_\_| \__,_|\__|\___/ ____/
Multi-Physics 9.4."3"-docs/add_python_processing_locally-eb00abccc7-FullDebug-x86_64
Compiled for GNU/Linux and Python3.11 with GCC-13.2
Compiled with threading and MPI support.
Maximum number of threads: 30.
Running without MPI.
Process Id: 502917
[[ 1. 4. 5. -1.]
[ 2. 6. 7. -1.]
[ 3. 8. 9. -1.]]