string type check in python

Question

I'm trying to do a type check with an element of a pandas dataframe which appears to be a string:

type(atmdf.ix[row]['bid'])

<type 'str'>

however, if I do a type check I get False:

type(atmdf.ix[row]['bid']) is 'str'

False

even with the isinstance I get the same unexpected result:

isinstance(type(atmdf.ix[row]['bid']), str)

False

where am I wrong?

P.S. the content of the dataframe is something like this:

atmdf.ix[row]['bid']
'28.5'

thank you!

Your second one is incorrect should be type(atmdf.ix[row]['bid']) is str — EdChum
– EdChum, Commented Oct 16, 2014 at 11:02

joris · Accepted Answer · 2014-10-16 11:01:38Z

2

You have to test the string itself with isintance, not the type:

In [2]: isinstance('string', str)
Out[2]: True

So in your case (leaving out the type(..)): isinstance(atmdf.ix[row]['bid'], str).

Your first check did not work because you have to compare to str (the type) not 'str' (a string).

answered Oct 16, 2014 at 11:01

joris

140k37 gold badges257 silver badges207 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

See comment of @EdChum: you have to compare to str not 'str'

@mspadaccino because you are comparing to a string 'str' rather than the type str

@mspadaccino : The type() function returns a type object, not a string.