Pandas: How to return rows where a column has a line breaks/new line ( \n ) in its cell?

Question

I am trying to return rows if a column contains a line break and specific word following it. So '\nWord'.

Here is a minimal example

testdf = pd.DataFrame([['test1', ' generates the final summary. \nRESULTS We evaluate the performance of ', ], ['test2', 'the cat and bat \n\n\nRESULTS\n teamed up to find some food'], ['test2' , 'anthropology with RESULTS pharmacology and biology']])
testdf.columns = ['A', 'B']
testdf.head()

>   A   B
>0  test1   generates the final summary. \nRESULTS We evaluate the performance of
>1  test2   the cat and bat \n\n\nRESULTS\n teamed up to find some food
>2  test2   anthropology with RESULTS pharmacology and biology

listStrings = { '\nRESULTS\n'}
testdf.loc[testdf.B.apply(lambda x: len(listStrings.intersection(x.split())) >= 1)]

This returns nothing.

The result I am trying to produce is return the first two rows since they contain '\nRESULTS' , but NOT the last row since it doesn't have a '\nRESULTS'

So

>   A   B
>0  test1   generates the final summary. \nRESULTS We evaluate the performance of
>1  test2   the cat and bat \n\n\nRESULTS\n teamed up to find some food

Answer 1

Usually we using str.contains with regex=False

testdf[testdf.B.str.contains('\n',regex=False)]

Answer 2

WeNYoBen's solution is better, but one with iloc and np.where would be:

>>> testdf.iloc[np.where(testdf['B'].str.contains('\n', regex=False))]
       A                                                  B
0  test1   generates the final summary. \nRESULTS We eva...
1  test2  the cat and bat \n\n\nRESULTS\n teamed up to f...
>>> 

Answer 3

Sometimes if they are very confusing text with a lot \t|\n|\r, it is not able to find them, I offer you a regular expression that collects all the cases

Example: this code will take all the columns WHERE \t|\n|\r appear

df_r = df_r[df_r["Name"].astype(str).str.contains(r"\\t|\\n|\\r", "\t|\n|\r",regex=True)]

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the answer has been inspired by: removing newlines from messy strings in pandas dataframe cells?