Differentially Private Set Union for Vocabulary Release

This repository contains the code and dataset for the following paper:

Differentially Private Set Union with Applications to Vocabulary Generation
Sivakanth Gopi, Pankaj Gulhane, Janardhan Kulkarni, Judy Hanwen Shen, Milad Shokouhi, and Sergey Yekhanin
https://arxiv.org/abs/2002.09745

Abstract: We study the basic operation of set union in the global model of differential privacy. In this problem, we are given a universe U of items, possibly of infinite size, and a database D of users. Each user i contributes a subset W_i of items. We want an (epsilon, delta)-differentially private Algorithm which outputs a subset S (a union of subsets W_i) such that the size of S is as large as possible. The problem arises in countless real world applications, and is particularly ubiquitous in natural language processing (NLP) applications. For example, discovering words, sentences, n-grams etc., from private text data belonging to users is an instance of the set union problem. In this paper we design new algorithms for this problem that significantly outperform the best known algorithms.

Prerequisites

python >= 3.6
numpy >= 1.14.3
pandas >= 0.22.0 
scipy >= 1.0.1
tqdm >= 4.23.4

Dataset

unzip data/clean_askreddit.csv.zip

The default dataset used in this repo is clean_askreddit.csv.
For your own input file, the file must contain an "author" and a "clean_text" column where the clean text has been preprocessed and tokenized. For an example, see utils.py.

Example: Generating a Histogram

python gen_histogram.py --save_histogram

This generates and saves a histogram with the Policy Gaussian algorithm and outputs the number of unigrams released.

python gen_histogram.py --alg policy --noise laplace --n 2 --trials 3

To change which algorithm is used specify the --alg and --noise parameter. To change the n of ngrams in the histogram use: --ngrams . For multiple shuffles of the dataset, use the --trials parameter.

Acknowledgments