# Macro "**relauncherFunctionFlowratePython.py**"

## Objective

The goal of this macro is to show how to handle the Python-written function in a full python-script. 
This function has been presented, at least its equation 
(see {eq}`flowrate_function`) and would be interface through the 
`TPythonEval` class in the {{Relaun}} module.

## Macro

{{
    "```{literalinclude} " + parent_dir
    + "/roottest/uranie/doc/relauncher/use_cases/" + language 
    + "/relauncherFunctionFlowratePython.py"
    + "\n"
    + ":language: python\n"
    + ":lines: 1-6,16-71\n"
    + "```"
}}

Obviously the code is now different from the other macros already introduced, but unless some 
python-specificity, the discussion has been largely done in [](#use_cases_macro_relauncher_cint_macro).

The first interesting part is the definition of the function `flowrateModel`. It is a classical 
python-function, for which every input is either a double, a list (for vectors) or a string. 
Disregarding the inner part, where the computation is done, the other interesting part is the return 
line: it should always be a list of all the objects that should be returned.

{{
    "```{literalinclude} " + parent_dir
    + "/roottest/uranie/doc/relauncher/use_cases/" + language 
    + "/relauncherFunctionFlowratePython.py"
    + "\n"
    + ":language: python\n"
    + ":lines: 17-24\n"
    + "```"
}}

Apart from this, the only other difference is the assessor construction which is an instance of the 
`TPythonEval` class as shown here:

{{
    "```{literalinclude} " + parent_dir
    + "/roottest/uranie/doc/relauncher/use_cases/" + language 
    + "/relauncherFunctionFlowratePython.py"
    + "\n"
    + ":language: python\n"
    + ":lines: 44-45\n"
    + "```"
}}

The macro is also leading to the creation of the following plot.

## Graph

{{
    "```{" "figure" "} " + parent_dir +
        "/roottest/build/uranie/doc/relauncher/use_cases/" + language 
        + "/python/relauncherFunctionFlowratePython.png\n"
    ":align: center\n"
    ":name: usecases_relauncherFunctionFlowratePython\n"
    + figure_scale + "\n"
    "\n"
    "Representation of the output as a function of the first input with a colZ option\n"
    "```"
}}