Strange behavior from custom matrix printer

[Alan Bromborsky]

I have implemented a custom matrix printer with "_print_MatrixBase(self, expr)."  I am running "jupyter notebook" with the output of 
"_print_MatrixBase(self, expr)" being given by -

    def _print_MatrixBase(self, expr):
        rows = expr.rows
        cols = expr.cols

        out_str = ' \\left [ \\begin{array}{' + (cols * 'c') + '} '
        for row in range(rows):
            for col in range(cols):
                out_str += latex(expr[row,col]) + ' & '
            out_str = out_str[:-2] + ' \\\\ '
        out_str = out_str[:-4] + ' \\end{array}\\right ] '

        if isinteractive():
            return display(Math(out_str))
        else:
            return out_str

for "jupyter notebook" the output is "return display(Math(out_str))" where the out_str ins the tex output for the matrix.  The notebook output is -

see Capture.PNG

Where  sp3.g is a sympy Matrix.  Why is "None"  output along with the correct matrix output?

[Aaron Meurer]

A better way to do this would be to define the LaTeX printer for the
object (which should be a separate printer from the pretty printer),
and enable LaTeX printing with init_printing().

Aaron Meurer

On Thu, Jul 2, 2015 at 10:30 AM, brombo <abrom...@gmail.com> wrote:
> I have implemented a custom matrix printer with "_print_MatrixBase(self,
> expr)." I am running "jupyter notebook" with the output of
> "_print_MatrixBase(self, expr)" being given by -
>
> def _print_MatrixBase(self, expr):
> rows = expr.rows
> cols = expr.cols
>
> out_str = ' \\left [ \\begin{array}{' + (cols * 'c') + '} '
> for row in range(rows):
> for col in range(cols):
> out_str += latex(expr[row,col]) + ' & '
> out_str = out_str[:-2] + ' \\\\ '
> out_str = out_str[:-4] + ' \\end{array}\\right ] '
>
> if isinteractive():
> return display(Math(out_str))
> else:
> return out_str
>
> for "jupyter notebook" the output is "return display(Math(out_str))" where
> the out_str ins the tex output for the matrix. The notebook output is -
>

> See attached file

>
> Where sp3.g is a sympy Matrix. Why is "None" output along with the
> correct matrix output?
>

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[Alan Bromborsky]

Using init_printing(use_latex= 'mathjax') solves the problem, but the person who found the problem said it was due to a bug in sympy.  I suggested that he send his observations to this group.

To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6L4V40%3DFL1oUSkPKSkDgcqkZJ4ZTXJ41BexTYwwLPVQCQ%40mail.gmail.com.

[Aaron Meurer]

This might be because without use_latex='mathjax', it tries to
generate the latex using matplotlib's TeX renderer, which doesn't
support all of latex.

Aaron Meurer

> https://groups.google.com/d/msgid/sympy/CALOxT-m4ue-%2Bwc5Mh_qZ05DDDxLs%3DRS9DvovFVvYFJn0rq4KVQ%40mail.gmail.com.

[Jason Moore]

We really need to fix this bug. It came up multiple times over SciPy.

Jason
moorepants.info
+01 530-601-9791

To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6%2BRX-%2Bmow4BQvrNVeMkVnJj%2BxnX2eyUGUasAgXkmZ%2BZSA%40mail.gmail.com.

[Aaron Meurer]

Specifically the "None" thing came up at SciPy?

Aaron Meurer

> https://groups.google.com/d/msgid/sympy/CAP7f1Aid5SHJ7KKxiL20CCvHgrjbG4pjvXaif0xC%2Bbj28w3vaQ%40mail.gmail.com.