import pandas as pd
import seaborn as sns

df = sns.load_dataset('titanic')
df.head(2)

	survived	pclass	sex	age	sibsp	parch	fare	embarked	class	who	adult_male	deck	embark_town	alive	alone
0	0	3	male	22.0	1	0	7.2500	S	Third	man	True	NaN	Southampton	no	False
1	1	1	female	38.0	1	0	71.2833	C	First	woman	False	C	Cherbourg	yes	False

df = df.loc[:, ['age', 'fare']]
df.head()

	age	fare
0	22.0	7.2500
1	38.0	71.2833
2	26.0	7.9250
3	35.0	53.1000
4	35.0	8.0500

6.1. DataFrame을 받고 DataFrame을 리턴하는 함수 매핑 -> DataFrame 반환

def missing_value(x: pd.DataFrame) -> pd.DataFrame:
    return x.isnull()

result_df = df.pipe(missing_value)
result_df.head()

	age	fare
0	False	False
1	False	False
2	False	False
3	False	False
4	False	False

6.2. DataFrame을 받고 Series를 리턴하는 함수 매핑 -> Series 반환

def missing_count(x: pd.DataFrame) -> pd.Series:
    return x.isnull().sum()

result_series = df.pipe(missing_count)
result_series

age     177
fare      0
dtype: int64

6.3. DataFrame을 받고 값을 리턴하는 함수 매핑 -> 값 반환

def total_number_missing(x: pd.DataFrame) -> int:
    return x.isnull().sum().sum()

result_value = df.pipe(total_number_missing)
result_value

177