org-mode call python source within latex source block

Question

I have a piece of python code that outputs latex code. I'm trying to call the python source block from within a latex source block so it will format the output as latex when I export.

Any idea how to do this? I was hoping something similar to the below would work.

#+name: gradient_potential
#+BEGIN_SRC python :exports none :results output
from sympy import symbols, sqrt, diff, latex

x, y = symbols('x y')

U = x * y

print(latex(diff(U, y)))
#+END_SRC


#+begin_export latex
\begin{align}
#+CALL: gradient_potential() :results output
\end{align}
#+end_export

Answer 1

Use a Noweb reference <<src block call>> to inject the results of source blocks into other source blocks.

Example:

#+NAME: ltxInput
#+BEGIN_SRC emacs-lisp :exports none :results raw drawer
"\\sqrt{x^2+y^2}"
#+END_SRC

#+RESULTS: ltxInput
:results:
\sqrt{x^2+y^2}
:end:


#+NAME: ltxSrc
#+BEGIN_SRC latex :noweb yes :exports results
\begin{align*}
<<ltxInput()>>
\end{align*}
#+END_SRC

#+RESULTS: ltxSrc
#+begin_export latex
\begin{align*}
\sqrt{x^2+y^2}
\end{align*}
#+end_export

Tested with Emacs 26.3 and Org 9.2.6.

Note that your approach with the :var header argument of a latex source block did not work for me. I got an error "Wrong use of \ in replacement string." for the slash in \sqrt{x^2+y^2}.

Answer 2

I found a way to do this, I'll post for anyone who has the same issue in the future. The method I found is using both a python source block and a latex source block.

#+name: gradient_potential_py
#+BEGIN_SRC python :exports none :results output :cache yes
from sympy import symbols, diff, latex

x, y = symbols('x y')

U = x * y

print(latex(diff(U, y)), end='')
#+END_SRC

#+name: gradient_potential
#+begin_src latex :var expr1=gradient_potential_py :exports none
\begin{align}
expr1
\end{align}
#+end_src

#+CALL: gradient_potential()

I found that I need the end='' in the print statement when exporting to latex.