在Python中检查变量是否为数字类型的最佳方法是什么

Question

I understand that I could use type() and isinstance() to check if a variable is of a certain type or belongs to certain class. I was wondering if there is a quick way to check if a variable is of a 'numeric' type, similar to isnumeric in MATLAB. It should return True if the variable is int, long, float, double, arrays of ints or floats etc. Any suggestions are greatly appreciated.

Thank you.

Answer 1

The easiest way to check if an object is a number is to do arithmethic operations (such as add 0) and see if we can get away with it:

def isnumeric(obj):
    try:
        obj + 0
        return True
    except TypeError:
        return False

print isnumeric([1,2,3]) # False
print isnumeric(2.5)     # True
print isnumeric('25')    # False

Answer 2

Check to see if each item can be converted to a float :

def mat_isnumeric(input):
    if type(input) is list:
        for item in input:
            if not is_a_number(item):
                return False
        return True
    else:
        return is_a_number(input)

def is_a_number(input):
    try:
        float(input)
        return True
    except ValueError:
        return False

Running the following script:

if __name__ == "__main__":
    print(mat_isnumeric(321354651))
    print(mat_isnumeric(3213543.35135))
    print(mat_isnumeric(['324234324', '2342342', '2343242', '23432.324234']))
    print(mat_isnumeric('asdfasdfsadf'))
    print(mat_isnumeric(['234234', '32432.324324', 'asdfsadfad']))

Produces this result:

True
True
True
False
False