Multi-task Learning Models for Recommender Systems

This project is developed based on DeepCTR :https://github.com/shenweichen/DeepCTR.

You can easy to use the code to design your multi task learning model for multi regression or classification tasks.

Model	Description	Paper
Shared-Bottom	Shared-Bottom	Multitask learning(1998)
ESMM	Entire Space Multi-Task Model	Entire Space Multi-Task Model: An Effective Approach for Estimating Post-Click Conversion Rate(SIGIR'18)
MMoE	Multi-gate Mixture-of-Experts	Modeling Task Relationships in Multi-task Learning with Multi-gate Mixture-of-Experts(KDD'18)
CGC	Customized Gate Control	Progressive Layered Extraction (PLE): A Novel Multi-Task Learning (MTL) Model for Personalized Recommendations(RecSys '20)
PLE	Progressive Layered Extraction	Progressive Layered Extraction (PLE): A Novel Multi-Task Learning (MTL) Model for Personalized Recommendations(RecSys '20)

Quick Start

from ple import PLE 

model = PLE(dnn_feature_columns, num_tasks=2, task_types=['binary', 'regression'],
            task_names=['task 1','task 2'], num_levels=2, num_experts_specific=8,
            num_experts_shared=4, expert_dnn_units=[64,64], gate_dnn_units=[16,16],
            tower_dnn_units_lists=[[32,32],[32,32]])

model.compile("adam", loss=["binary_crossentropy", "mean_squared_error"], metrics=['AUC','mae'])

model.fit(X_train, [y_task1, y_task2], batch_size=256, epochs=5, verbose=2)

pred_ans = model.predict(X_test, batch_size=256)

Example 1

Dataset: http://archive.ics.uci.edu/ml/machine-learning-databases/adult/

Task 1: (Classification) aims to predict whether the income exceeds 50K.

Task 2: (Classification) aims to predict this person’s marital status is never married.

Dataset: https://archive.ics.uci.edu/ml/machine-learning-databases/census-income-mld/

Example 2

Census-income Dataset contains 299,285 samples and 40 features extracted from the 1994 census database.

Group 1

Task 1: (Classification) aims to predict whether the income exceeds 50K.

Task 2: (Classification) aims to predict this person’s marital status is never married.

Group 2

Task 1: (Classification) aims to predict whether the education level is at least college.

Task 2: (Classification) aims to predict this person’s marital status is never married.

Experiment Setup (follow MMOE paper) :

#Parameters
learning_rate = 0.01 #Adam
batch_size = 1024

#ESMM
Tower Network: hidden_size=8
  
#Shared-Bottom
Bottom Network: hidden_size = 16
Tower Network: hidden_size=8

#MMOE
num_experts = 8
Expert Network: hidden_size=16
Tower Network: hidden_size=8

#CGC
num_experts_specific=4
num_experts_shared=4
Expert Network: hidden_size=16
Tower Network: hidden_size=8

#PLE
num_level = 2

Experiment Results (AUC)

Model	Group1 Income	Group1 Marital Stat	Group2 Education	Group2 Marital Stat
Shared-Bottom	0.9478	0.9947	0.8745	0.9945
ESMM	0.9439	0.9904	0.8601	0.982
MMoE	0.9463	0.9937	0.8734	0.9946
CGC	0.9471	0.9947	0.8736	0.9946
PLE	0.948	0.9947	0.8737	0.9945

Notes: We do not implement a hyper-parameter tuner as MMoE paper done. In ESSM experiment, we treat task 2 as CTR and task 1 as CTCVR.

Shared-Bottom & MMOE

ESMM

CGC

PLE