Why can't I chain the get_dummies() function?
import pandas as pd df = (pd .read_csv('https://raw.githubusercontent.com/mwaskom/seaborn-data/master/iris.csv') .drop(columns=['sepal_length']) .get_dummies() ) This works fine:
df = (pd .read_csv('https://raw.githubusercontent.com/mwaskom/seaborn-data/master/iris.csv') .drop(columns=['sepal_length']) ) df = pd.get_dummies(df) DataFrame.pipe can be helpful in chaining methods or function calls which are not natively attached to the DataFrame, like pd.get_dummies:
df = df.drop(columns=['sepal_length']).pipe(pd.get_dummies) Or with lambda:
df = ( df.drop(columns=['sepal_length']) .pipe(lambda current_df: pd.get_dummies(current_df)) ) Sample DataFrame:
df = pd.DataFrame({'sepal_length': 1, 'a': list('ABACC'), 'b': list('ACCAB')}) df:
sepal_length a b 0 1 A A 1 1 B C 2 1 A C 3 1 C A 4 1 C B Sample Output:
df = df.drop(columns=['sepal_length']).pipe(pd.get_dummies) df:
a_A a_B a_C b_A b_B b_C 0 1 0 0 1 0 0 1 0 1 0 0 0 1 2 1 0 0 0 0 1 3 0 0 1 1 0 0 4 0 0 1 0 1 0 You can't chain the pd.get_dummies() method since it is not a pd.DataFrame method. However, assuming -
... you can use pd.Series.str.get_dummies() which is a series level method.
### Dummy Dataframe # A B # 0 1 x # 1 2 y # 2 3 z pd.read_csv(path).drop(columns=['A'])['B'].str.get_dummies() x y z 0 1 0 0 1 0 1 0 2 0 0 1 NOTE: Make sure that before you call the get_dummies() method, the data type of the object is series. In this case, I fetch column
['B']to do that, which kinda makes the previouspd.DataFrame.drop()method unnecessary and useless :)But this is only for example's sake.
get_dummiesis a pandas function not a method for dataframe. In the first try, you're trying tp apply a function on a dataframe.pd.Series.str.get_dummies()which is a series method. Details in my answer.