When setting a column name for a pandas dataframe, why does the following work:

df_coeff = pd.DataFrame(data = lm.coef_, index = X.columns, columns = ['Coefficient'])

While this does not work

df_coeff = pd.DataFrame(data = lm.coef_, index = X.columns, columns = 'Coefficient')

Why are brackets required around the column name? What is Python doing here?

Thanks

The DataFrame constructor expects an "Index or array-like" as the column argument.

• ['Coefficient'] is a Python list with a single entry, the string 'Coefficient'.
• 'Coefficient' is not a list, but just a string.

DataFrame accepts a Python list, but not a string, as an array-like.