# Parallel coordinates¶

## Preliminaries: instantiation and execution of the MDO scenario¶

Let’s start with the following code lines which instantiate and execute the `MDOScenario`

:

```
from gemseo.api import create_discipline, create_scenario
formulation = 'MDF'
disciplines = create_discipline(["SobieskiPropulsion", "SobieskiAerodynamics",
"SobieskiMission", "SobieskiStructure"])
scenario = create_scenario(disciplines,
formulation=formulation,
objective_name="y_4",
maximize_objective=True,
design_space="design_space.txt")
scenario.set_differentiation_method("user")
algo_options = {'max_iter': 10, 'algo': "SLSQP"}
for constraint in ["g_1","g_2","g_3"]:
scenario.add_constraint(constraint, 'ineq')
scenario.execute(algo_options)
```

## ParallelCoordinates¶

### Description¶

The `ParallelCoordinates`

post processing
builds parallel coordinates plots among design
variables, outputs functions and constraints

The `ParallelCoordinates`

portray the design variables history during the
scenario execution. Each vertical coordinate is dedicated to a design
variable, normalized by its bounds.

A polyline joins all components of a given design vector and is colored by objective function values. This highlights correlations between values of the design variables and values of the objective function.

x- and y- figure sizes can be changed in option. It is possible either to save the plot, to show the plot or both.

### Options¶

**extension**,`str`

- file extension**figsize_x**,`Unknown`

- X size of the figure Default value = 10**figsize_y**,`Unknown`

- Y size of the figure Default value = 2**file_path**,`str`

- the base paths of the files to export**save**,`bool`

- if True, exports plot to pdf**show**,`bool`

- if True, displays the plot windows

## Case of the MDF formulation¶

To plot the parallel coordinates, use the API method `execute_post()`

with the keyword `"ParallelCoordinates"`

and
additional arguments concerning the type of display (file, screen, both):

```
scenario.post_process("ParallelCoordinates", save=True, show=False, file_path="mdf" )
```

Figures Quadratic approximation on the Sobieski use case for the MDF formulation and Quadratic approximation on the Sobieski use case for the MDF formulation show parallel coordinates respectively of the design variables and the constraints, colored by objective function value. The minimum objective value, in dark blue, corresponds to satisfied constraints.