import pandas as pd
from petl import cut, look, tocsv, fromcsv
import numpy as np
from sklearn.tree import DecisionTreeClassifier

Location = r'D:\python\Py\titanic.csv'
datapetl = fromcsv(Location)
data_fa = cut(datapetl,'Pclass', 'Fare', 'Age', 'Sex')
tocsv(data_fa, r'D:\python\Py\titanic_fa2.csv')
new_location = r'D:\python\Py\titanic_fa2.csv'

data_raw = pd.read_csv(Location, index_col='PassengerId')
df_withna = pd.read_csv(new_location)
df = df_withna[['Pclass', 'Fare', 'Age', 'Sex']].dropna()
print df
clf = DecisionTreeClassifier()