Why am I getting an Attribute error on a string object?

Question

Depending on which classroom a pupil is in, I would like to return one of two values and assign it to the variable name 'scoreMutiplier' which would then be used later elsewhere in my code. However, I am still pretty new to this and have been confronted with the following error message after the first scenario when I execute my code: AttributeError: 'str' object has no attribute 'isin'

import numpy as np

pupil = 'Tom'

classroom_A = ['Peter', 'Greg', 'Susan', 'Tom', 'John']

classroom_B = ['Steve', 'Joe', 'Jose', 'Pam', 'Paul']

scenario = [((pupil.isin(classroom_A )) & (~pupil.isin(classroom_B ))),
            ((pupil.isin(classroom_B )) & (~pupil.isin(classroom_A )))]

result = [3,1]

scoreMultiplier = np.select(scenario , result, default='')

print(scoreMultiplier)

What is the best way to make this work?

Many thanks in advance.

Marko · Accepted Answer · 2020-10-25 16:50:50Z

1

You got the right idea, but are using the wrong function. A str object does not have an isin() function. You should use the keyword in which, in the case of a list, check if the list contains the given object (in other cases it calls the object's __contains__() function). You should also use Python's binary operators (and, or, not) when working with boolean instead of bitwise operators. So that would mean to change this part of the code to the following:

scenario = [pupil in classroom_A and pupil not in classroom_B,
            pupil in classroom_B and pupil not in classroom_A]

edited Oct 25, 2020 at 16:50

answered Oct 25, 2020 at 16:40

Marko

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3 Comments

windwalker Over a year ago

Thanks thats seems to have done it. However, I got a warning message:- DeprecationWarning: select condlists containing integer ndarrays is deprecated and will be removed in the future. Use .astype(bool) to convert to bools. This actually prevented the use of the variable in a calculation further down in my code, which I got around by converting the variable to a float. But how should I change my code to comply with what the warning message is suggesting?

Marko Over a year ago

It's hard to answer this only through comments, I don't know which variable is this concerning. When I run the above code there is no warning message.

windwalker Over a year ago

"....You should also use Python's binary operators (and, or, not) when working with boolean instead of bitwise operators...' your explanation and the amendment @Samansi Hymavathi address the final problem that I was having perfectly. Ace!!!!!!

Samsani Hymavathi · Accepted Answer · 2020-10-25 18:06:26Z

0

Check this code:

import numpy as np

pupil = 'Tom'

classroom_A = ['Peter', 'Greg', 'Susan', 'Tom', 'John']

classroom_B = ['Steve', 'Joe', 'Jose', 'Pam', 'Paul']

scenario = [pupil in classroom_A and pupil not in classroom_B,
            pupil in classroom_B and pupil not in classroom_A]

result = [3,1]

scoreMultiplier = np.select(scenario , result, default='')

print(scoreMultiplier)

answered Oct 25, 2020 at 18:06

Samsani Hymavathi

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