Cannot use greek letter with the LaTeX format about pyphs

[afalaize]

Hi;

Thank you for your interest, and, please, note that standard rules of politeness apply here ;)

In short: It is not possible to use latex syntax in python(/sympy). In some cases (e.g. matplotlib plot titles and legends), it is possible to render in math mode "$\pi$". We could build a wrapper in pyphs that would basically escapes every backslashes when necessary, but it is not a priority.

I don't understand why you "need" latex symbols.

If you are looking for fancy printing in python interpreter, you can use this sympy module, or simply the capabilities of sympy regarding pretty printing of maths:

>>> import sympy
>>> sympy.init_printing()  # activate sympy pretty printing
>>> pi = sympy.symbols('pi_1')  # notice there is no backslash
>>> pi   # display nicely most latex symbols
π₁

I you want LaTeX commands for symbols in the generated LaTeX files, I suggest that (i) you use standard names for symbols in pyphs (e.g. "pi_i"), and (ii) make a query/replace in the generated LaTeX file to get the proper command (e.g. search "pi_i" => replace by "\pi_i").

Sorry, no solution out of the box, but this a standard python/sympy/pyphs behavior, not an issue.
I close, and you can open a thread in the mailing list to ask other pyphs users.

[FabricioS]

Hi Antoine, Hi Victor,
as mentioned by Antoine, Sympy handles (under the hood) many latex symbols, including greek letters. For instance
xk, k = core.symbols([ '\\xi_i','k' ])
can simply be changed to
xk, k = core.symbols([ 'xi_i','k' ])
and the xk python variable will be represented by the appropriate $\xi_i$ in the ipython shell, jupyter notebook and the latex report generated by PyPHS.

Best regards

[WetzelVictor]

Hi Antoine, Hi Fabrice

Thank you for your answers! You solved my problems :)

[afalaize]

Hi!
@FabricioS The rendering of symbols in the latex report generated by PyPHS is controlled in the symbol_names function (line 14 in pyphs/pyphs/misc/latex/tools.py):

def symbol_names(core):
    sn = {}
    for var in [r'x', 'dx', r'w', r'u', r'y', r'cy', r'p', r'o', r'g', r'z_symbols']:
        for symb in geteval(core, var):
            string = str(symb)
            lab = string[1:]
            sn.update({symb: string[0]+r'_{\mathrm{'+lab+r'}}'})
    for symb in core.subs.keys():
        string = str(symb)
        lab = string[1:]
        sn.update({symb: string[0]+r'_{\mathrm{'+lab+r'}}'})
return sn

In short, the (nowhere written) rule is: the first character of the symbol's string is the variable, the remaining part is the variable label: the symbol "xstiff" will be rendered as $x_{\mathrm{stiff}}$.

@WetzelVictor you can redesign the function symbol_names to your needs, and submit it as a pull request if you think it's worth it.

I admit we could do a lot regarding the rendering of PyPHS structures, but again this is not a priority.

All the best;

Antoine