Question

I have a dictionary:

self.currently_occupied = {obj:[0, 0]}

I need to check if the value of obj contains anything other than two numbers in a list

Example:

obj:[58, -234]  is ok
obj:[32]        is not 
obj:[]          is not
obj:[4, k]      is not

Answer 1

My solution is to large extent based on @Levon’s solution, but I am adding one more detail. Just using is isinstance can lead some lists that are not composed of numbers to qualify. For example:

[float('nan'), float('inf')]

would qualify because technically both above values are float; however, they are not numbers; therefore we need to add an additional condition to control for that.

import numpy as np

def check(x):
    if isinstance(x,list):
        if len(x) == 2:
            if all(isinstance(ele, (int, float)) and np.isinf(ele) == False and np.isnan(ele) == False for ele in x):
                return True
    return False

Result:

>>> check([2,3])
True
>>> check([4, float('inf')])
False

EDIT:

I think the use of isfinite makes the code cleaner, and I also think that we don’t need to use isinstance in this case. The resulting code would be:

def check(x):
    if isinstance(x,list):
        if len(x) == 2:
            if all(np.isfinite(ele) for ele in x):
                return True
    return False