Python (SymPy, SciPy), create symbol lambda from string

Question

I've struggling to take text inputs of an equation and evaluate it as a definite integral. I need a callable function to pass to scipy.integrate.

eq = "x**2"
func = lambda x: eq
func(2)

# outputs:
# x**2


# but if I:

func = lambda x: x**2
func(2)

# outputs:
# 4

Answer 1

Not sure, but maybe you are looking for

eq = "x**2"
func = eval("lambda x: " + eq)

Note that using eval() is dangerous if eq is from an untrusted source (e.g. user input).

Answer 2

You need to use eval to run eq as code and not treat it as a string.

eq = "x**2"
func = lambda x: eval(eq)
func(2)

# outputs:
# 4