df_m.py

import pandas as pd
from sklearn.neighbors import KNeighborsRegressor
from sklearn.metrics import mean_squared_error

train = {'author': ['green', 'white'],
         'age': [21, 34],
         'pages': [100, 200],
         }

train = pd.DataFrame(train)
print(train.head())

features = ['pages', 'age']

train_age = train.loc[train['age'].between(25, 34)]

print(train_age)
print(train_age[features])

for i, d in train.iterrows():
    print(d[features])
    age = d['age']
    print(age)