Convert list of strings SymPy to symbols and use in solveset

The post “How can I convert a list of strings into sympy variables?” discusses how to generate SymPy symbols from a list of strings. My question is what steps are needed to use these symbols x, y and z in SymPy calculations?

I tried something along the lines

from sympy import symbols, solveset

var_as_strings = ['x', 'y', 'z']
var_as_symbol_objects = [sympy.symbols(v) for v  in var_as_strings]
var_as_symbol_objects

for x1, x2 in zip(var_as_symbol_objects, var_as_strings):
    x1 = symbols(x2)

soln = solveset(x-y-z, x)

but I get the error “NameError: name ‘x’ is not defined”. Any help is greatly appreciated.

Answer

You can create Python variables in the current namespace from a list of strings (or a string of space or comma separated names) with var:

>>> names = 'x y z'  # or 'x, y, z'
>>> var(names)
(x, y, z)
>>> var(list('xyz'))
[x, y, z]
>>> var(set('xyz'))
{x, y, z}

In all cases, after issuing the var command you will be able to use variables that have been assigned SymPy symbols with the same name.