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pythonexpressioncall

How to call expressions and assign them values

I have a dictionary of many expressions, for example 

g={'asd':x+y,'sss':x-y}

I would like to define two functions aa and bb that return the evaluated value of these expressions.

g={'asd':x+y,'sss':x-y}
def aa(x,y):
    return g['asd']
def bb(x,y):
    return g['sss']
aa(2,3)

However, I cannot make it correct.

Does anyone know how to do this in python?

Moreover, in fact I have many variables rather only x,y, but variables like x1,x2,x3...x100. I also have many functions.

If to do it this way:

g = { 'asd': lambda x, y: math.exp(x)**y, 'sss': lambda x, y: x - y }
def aa(x,y):
    return g['asd'](x,y)
def bb(x,y):
    return g['sss'](x,y)
bb(2,3)

I will have to copy x1,x2,x3...x100 for 100 times. This is too huge.

Solution

  • You can use eval:

    g={'asd':'x+y','sss':'x-y'}
def aa(x,y):
    return eval(g['asd'])
def bb(x,y):
    return g['sss']
aa(2,3)