在Python 3.7中计算列表

Question

I was wondering if it was possible to calculate a list, for example this one

calculation = [1, "+", 2, "*", 15]

so it returns 31.

Answer 1

Don't use eval ever. Check this post

Instead you can refer some other library like asteval

from asteval import Interpreter
aeval = Interpreter()
calculation = [1, "+", 2, "*", 15]
aeval.eval(''.join(map(str, calculation)))

Answer 2

Maybe you could take a look at a binary expression tree.

binary expression tree

Answer 3

Sure:

eval(' '.join(map(str, calculation)), {}, {})

The inner join (no pun intended) builds a single string which is valid Python code, then you simply eval() it.

The two {} s are optional, they make it so the code runs without access to the surrounding global and local variables.

Answer 4

eval can be used for evaluating an expression (which is in the form of a string) in python.

Desired output can be obtained as below

eval(''.join([str(x) for x in calculation]))