Python eval function with numpy arrays via string input with dictionaries

Question

I am implementing the code in python which has the variables stored in numpy vectors. I need to perform simple operation: something like (vec1+vec2^2)/vec3. Each element of each

Answer 1

Pass the dictionary to python eval function:

>>> var = {'a':np.array([1,2,2]),'b':np.array([2,1,3]),'c':np.array([3])}
>>> formula = '2*a*(b/c)**2'
>>> eval(formula, var)
array([ 0.8889,  0.4444,  4.    ])

Answer 2

Using numexpr, then you could do this:

In [143]: import numexpr as ne
In [146]: ne.evaluate('2*a*(b/c)**2', local_dict=var)
Out[146]: array([ 0.88888889,  0.44444444,  4.        ])