filling missing value python

preprocessing.py

import pandas as pd
import sklearn as sk
# import the dataset
dataset = pd.read_csv(‘db.csv’)
# Load all columns into matrix but not the last ones
x = dataset.iloc[0:12,0:5].values
# Last column from the dataset
y = dataset.iloc[0:12,6].values
# Use the mean for fill missing data
imputer = sk.preprocessing.Imputer()
imputer = imputer.fit(x[0:12,3:5])
x[0:12,3:5] = imputer.transform(x[0:12,3:5])
# now the missing value will be filled with the mean of the column