如何在Python中使用isinstance检查float？

Question

I cannot make sense of below: When I check the type of "RUN_ID", it clearly states "float". But when I check if it is float, it returns False. What is this type exactly and how to check?

tags.loc[0, 'RUN_ID']
Out[36]: 38607.0   
type(tags.loc[0, 'RUN_ID'])
Out[34]: float 
isinstance(type(tags.loc[0, 'RUN_ID']),np.float64)
Out[32]: False
isinstance(type(tags.loc[0, 'RUN_ID']),np.float32)
Out[33]: False

isinstance(type(tags.loc[0, 'RUN_ID']),float)
Out[35]: False

Answer 1

You're using isinstance wrong. Instead of

isinstance(type(tags.loc[0, 'RUN_ID']),float)

just do

isinstance(tags.loc[0, 'RUN_ID'],float)

The type() function returns an object of type type , where you want the type of the object itself.

Answer 2

isinstance(type(tags.loc[0, 'RUN_ID']),float) 

returns false because type(tags.loc[0, 'RUN_ID']) returns float , which is actually of type type . You can verify that by saying something like

type(type(tags.loc[0, RUN_ID'])) 

So you're actually checking to see if the type of the type float is the same as the type float , which is False .

So maybe try

isinstance(tags.loc[0, 'RUN_ID'],float)?

Answer 3

check with the regular float type instead of numpy. Test results below

w = isinstance(n, float)    # True
x = isinstance(n, np.float32)   # False
y = isinstance(n, np.float64)   # False
z = type(n) == float        # True

Answer 4

I believe isinstance() checks more if a value is a certain class rather than if two class values are the same.

For example, isinstance(0.35, float) returns True.

The way you have it is basically asking "Is the type float an instance of a float?" which is not correct.