How to assert all values in a Pandas dataframe's column have a desired length

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I have Pandas dataframe, that has the length of "state" column. I am 100% sure, the length of all the values in the column is 2. When I try to write an assert statement, I am getting an assertion error. I am not sure if I am using the assert statement correctly. Please help.

assert df['state'].str.len().all() == 2

My understanding: assert that all the values in the state column have a length that is equal to 2. Please let me know if this is correct. Thank You.

pandas dataframe assert python
1 Answers

You have the order a bit messed up.

In your code df['state'].str.len().all() checks if all the lengths are different from 0, which returns a single True/False or 1/0. And when you compare that to a single 2, it's always False and trigger the assert.

It should be:

assert (df['state'].str.len() == 2).all()
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