# cqf
A General-Purpose Counting Filter: Counting Quotient Filter (CQF)

Overview
--------

Squeakr a k-mer-counting and multiset-representation system using the
recently-introduced counting quotient filter (CQF) Pandey et al. (2017), a
feature-rich approximate membership query (AMQ) data structure.

Squeakr is memory-efficient, consuming 1.5X–4.3X less memory than the
state-of-the-art. It offers competitive counting performance, and answers
queries about a particular k-mer over an order-of- magnitude faster than other
systems. The Squeakr representation of the k-mer multiset turns out to be
immediately useful for downstream processing (e.g., De Bruijn graph traversal)
because it supports fast queries and dynamic k-mer insertion, deletion, and
modification.

API
--------
* 'main': count k-mers in a read dataset
* 'inner-prod': compute inner products of two Squeakr representations

Build
-------
This library depends on libssl and boost.

```bash
 $ make main
 $ ./main 0 20 1 test.fastq
```

 Following are the argumenrs to main:
 - file format: 0 - plain fastq, 1 - gzip compressed fastq, 2 - bzip2 compressed fastq
 - CQF size: the log of the number of slots in the CQF
 - num of threads: number of threads to count
 - file(s): "filename" or "dirname/*" for all the files in a directory

```bash
 $ make inner-prod
 $ ./inner-prod file1 file2
```
 
 Following are the argumenrs to inner-prod:
 - file1: dataset 1 Squeakr representation
 - file2: dataset 2 Squeakr representation

Contributing
------------
Contributions via GitHub pull requests are welcome.


Authors
-------
- Prashant Pandey <ppandey@cs.stonybrook.edu>
- Rob Patro <rob.patro@cs.stonybrook.edu>
- Rob Johnson <rob@cs.stonybrook.edu>