California Housing Dataset

Modifying California Housing Dataset

We are using the California Housing Dataset to create a real data example dataset for NannyML. There are three steps needed for this process:

  • Enriching the data

  • Training a Machine Learning Model

  • Meeting NannyML Data Requirements

To find out what requirements NannyML has for datasets, check out Data Requirements.

We need to start by loading the dataset.

>>> # Import required libraries
>>> import pandas as pd
>>> import numpy as np
>>> import datetime as dt

>>> from sklearn.datasets import fetch_california_housing
>>> from sklearn.ensemble import RandomForestClassifier
>>> from sklearn.metrics import roc_auc_score

>>> cali = fetch_california_housing(as_frame=True)
>>> df = pd.concat([cali.data, cali.target], axis=1)
>>> df.head(2)

MedInc

HouseAge

AveRooms

AveBedrms

Population

AveOccup

Latitude

Longitude

MedHouseVal

0

8.3252

41

6.98413

1.02381

322

2.55556

37.88

-122.23

4.526

1

8.3014

21

6.23814

0.97188

2401

2.10984

37.86

-122.22

3.585

Enriching the data

The things that need to be added to the dataset are:

  • A time dimension

  • Splitting the data into reference and analysis sets

  • A binary classification target

>>> # add artificial timestamp
>>> timestamps = [dt.datetime(2020,1,1) + dt.timedelta(hours=x/2) for x in df.index]
>>> df['timestamp'] = timestamps

>>> # add periods/partitions
>>> train_beg = dt.datetime(2020,1,1)
>>> train_end = dt.datetime(2020,5,1)
>>> test_beg = dt.datetime(2020,5,1)
>>> test_end = dt.datetime(2020,9,1)
>>> df.loc[df['timestamp'].between(train_beg, train_end, inclusive='left'), 'partition'] = 'train'
>>> df.loc[df['timestamp'].between(test_beg, test_end, inclusive='left'), 'partition'] = 'test'
>>> df['partition'] = df['partition'].fillna('production')

>>> # create new classification target - house value higher than mean
>>> df_train = df[df['partition']=='train']
>>> df['clf_target'] = np.where(df['MedHouseVal'] > df_train['MedHouseVal'].median(), 1, 0)
>>> df = df.drop('MedHouseVal', axis=1)
>>> del df_train

Training a Machine Learning Model

>>> # fit classifier
>>> target = 'clf_target'
>>> meta = 'partition'
>>> features = ['MedInc', 'HouseAge', 'AveRooms', 'AveBedrms', 'Population', 'AveOccup', 'Latitude', 'Longitude']


>>> df_train = df[df['partition']=='train']

>>> clf = RandomForestClassifier(random_state=42)
>>> clf.fit(df_train[features], df_train[target])
>>> df['y_pred_proba'] = clf.predict_proba(df[features])[:,1]
>>> df['y_pred'] = df['y_pred_proba'].map(lambda p: int(p >= 0.8))

>>> # Check roc auc score
>>> for partition_name, partition_data in df.groupby('partition', sort=False):
...     print(partition_name, roc_auc_score(partition_data[target], partition_data['y_pred_proba']))
train 1.0
test 0.8737681614409617
production 0.8224322932364313

Meeting NannyML Data Requirements

The data are now being split to satisfy NannyML format requirements.

>>> df_for_nanny = df[df['partition']!='train'].reset_index(drop=True)
>>> df_for_nanny['partition'] = df_for_nanny['partition'].map({'test':'reference', 'production':'analysis'})
>>> df_for_nanny['identifier'] = df_for_nanny.index

>>> reference = df_for_nanny[df_for_nanny['partition']=='reference'].copy()
>>> analysis = df_for_nanny[df_for_nanny['partition']=='analysis'].copy()
>>> analysis_target = analysis[['identifier', 'clf_target']].copy()
>>> analysis = analysis.drop('clf_target', axis=1)

The reference dataframe represents the reference Data Period and the analysis dataframe represents the analysis period. The analysis_target dataframe contains the targets for the analysis period, which is provided separately.