dictionary key type confusion isinstance python

Question

I can't understand following execution. I expected different results.

>>> f = {'ms':'ma'}
>>> isinstance(f['ms'], type(str))
False

>>> isinstance(f['ms'], type(dict))
False

>>> type(f['ms'])
<class 'str'>

`type(str)` returns `type`, so you are checking if `f['ms']` is an instance of `type`, not an instance of `str`. If you want to check if something is a string, use `isinstance(f['ms'], str)`. — khelwood, Nov 15 '18 at 11:42

khelwood · Accepted Answer · 2018-11-15T12:50:59.917

4

type(str) and type(dict) each return type, so you are checking if your objects are instances of type, which they are not.

If you want to check if something is a string, use

isinstance(f['ms'], str)

not

isinstance(f['ms'], type(str))

And if you want to test if something is a dict, you can use

isinstance(f['ms'], dict)

not

isinstance(f['ms'], type(dict))

edited Nov 15 '18 at 12:50

answered Nov 15 '18 at 11:46

khelwood

score 1 · Answer 2 · answered Nov 15 '18 at 11:42

1

I think you just want this:

>>> f = {'ms':'ma'}
>>> isinstance(f['ms'], str)
True

You don't need type(str)

answered Nov 15 '18 at 11:42

richflow

2 Answers2