Objective and scope¶
This section describes how to use
The idea is to help the users to define the right MDO problem to be solved, even before wrapping any software.
The result of the study are a N2 (or DSM)
and XDSM diagrams (see more explanations here XDSM),
with a defined MDO problems including:
The list of disciplines, with their inputs and outputs
The design variables
The objective function(s)
No executable code is produced, the idea is to assist the discussions with design and field experts, customers, to define the MDO problem, from the white sheet. This way, the study may be visualized before any process or tool being actually ready.
There is no need to write any line of code to use this tool. A command line executable is available.
The next figure illustrates how this tool can be used to create an MDO study analysis. This requires the creation of an excel workbook with one sheet per discipline. The name of the discipline is given by the name of the sheet. On each of these sheets, the inputs and outputs of the discipline must be given.
Scenarios are defined by sheet names starting with “Scenario”.
The N2 and XDSM diagrams can be generated from such as study file. The N2 diagrams are generated as pdf files. The XDSM diagrams are generated as standalone HTML files, by default, or as Latex and pdf files as an option (-l).
For more complex use cases, multi-level formulations can also be used.
You first need to define the sub-scenarios in dedicated sheets,
and then add the names of these sheets in the cell block “Disciplines” of the sheet defining the main scenario.
Finally, a multilevel MDO formulation has to be chosen, e.g.
- class gemseo.utils.study_analysis.StudyAnalysis(xls_study_path)
A MDO study analysis from an Excel specification.
Generate a N2 (equivalent to the Design Structure Matrix) diagram, showing the couplings between the disciplines, and a XDSM (Extended Design Structure Matrix), showing the MDO process, from an Excel specification of the inputs, outputs, design variables, objectives and constraints.
The input Excel files contains one sheet per discipline. The name of the sheet shall have the discipline name. The sheet shall have at least two columns, one for inputs and one for outputs, with the following format:
Empty lines are ignored.
The scenarios (at least one, or multiple for distributed formulations) must appear in a Excel sheet name starting by “Scenario”.
The sheet shall have the following columns, with some constraints :
All of them are mandatory, even if empty for the constraints.
The order does not matter.
One and only one formulation must be declared.
At least one objective must be provided, and one design variable.
All the objective functions and constraints must be outputs of a discipline, not necessarily the one of the current sheet. All the design variables must be inputs of a discipline, not necessarily the one of the current sheet.
The columns ‘Options’ and ‘Options values’ are used to pass the formulation options. Note that for string type ‘Option values’, the value can be written with or without the “” characters.
To use multi level MDO formulations, create multiple scenarios, and add the name of the sub scenarios in the list of disciplines of the main (system) scenario.
An arbitrary number of levels can be generated this way (three, four levels etc formulations).
Initialize the study from the Excel specification.
xls_study_path (str | Path) – The path to the Excel file describing the study.
- generate_n2(file_path='n2.pdf', show_data_names=True, save=True, show=False, fig_size=(15, 10))
Generate a N2 plot for the disciplines list.
file_path (str) –
The file path of the figure.
By default it is set to “n2.pdf”.
show_data_names (bool) –
If true, the names of the coupling data is shown; otherwise, circles are drawn, which size depends on the number of coupling names.
By default it is set to True.
save (bool) –
If True, save the figure to file_path.
By default it is set to True.
show (bool) –
If True, show the plot.
By default it is set to False.
The size of the figure.
By default it is set to (15, 10).
- Return type:
- generate_xdsm(output_dir, latex_output=False, open_browser=False)
Create a xdsm.json file from the current scenario.
The MDOScenario that contains the DesignSpace, the formulation, but the disciplines have only correct input and output grammars but no _run methods so that can’t be executed
- Return type:
- disciplines_descr: dict[str, MDODiscipline]
The descriptions of the disciplines (including sub-scenario) parsed in the Excel file.
- scenarios_descr: dict[str, dict[str, str | list[str]]]
The descriptions of the scenarios parsed in the Excel file.
- study: XLSStudyParser
The XLSStudyParser instance built from the Excel file.
- xls_study_path: str
The path of the Excel file.
Usage of the command line executable¶
GEMSEO installation provides the gemseo-study command line executable, its usage is:
gemseo-study [-h] [-o OUT_DIR] [-x] [-l] [-s FIG_SIZE] study_file
A tool to generate an N2 chart and an XDSM diagram from an Excel description file.
- positional arguments:
study_file XLS file that describes the study
- optional arguments:
- -h, --help
show this help message and exit
- -o OUT_DIR, --out_dir OUT_DIR
Output directory for the generated files
- -x, --xdsm
If True, generates the XDSM file
- -l, --latex_output
If True, generates the XDSM in PDF and Latex
- -s FIG_SIZE, --fig_size FIG_SIZE
Size of the N2 figure, tuple (x,y)