pponakala/longreadsmapping

Long Reads Mapping Algorithms

Long Read Mapping Algorithms

Output:

• Simulated Data
• Min Hash algorithm implemented in C++
• Containment Hash algorithm implemented in C++
• Mapper function

Files:

• Generate Simulated Data: generate_data.py
• Min Hash and Containment Hash algorithms: hash.cpp, hash.h
• Comparing both approaches: main.cpp
• Plotting graphs: draw_graphs.py
• Mapper function: mapper.cpp
• Scripts: run.sh, query.sh

Applications in real life:

• Taxonomic classification
• To detect presence or absence of genome in metagenomics sample
• To detect the presence of very small, low abundance microorganisms in a metagenomic data set

Instructions:

1. Estimate Jaccard Index by running Min Hash and Containment Min Hash.

./run.sh <file1> <file2> <kmer_size> <hash_functions>
 <false_positive_rate> <number_appended_to_results_files> <order_of_len_A> <order_of_len_B>

./run.sh data/file3.txt data/file4.txt 20 200 0.01 2 150 1000

./run.sh data/file1.txt data/file2.txt 18 1000 0.02 3 15 1000

Sample output:

2. Compare both approaches. Reproduce the graphs in the report.

./run.sh data/filex3.txt data/filex4.txt 20 150 0.04 3

./run.sh data/filex1.txt data/filex2.txt 25 1000 0.01 4

Sample output:

3. Mapping long reads: Script generates reference genome and long reads and then maps long reads to reference genome if they have similarity higher than threshold.

./query.sh <long_reads_file> <reference_genome_file> <threshold>
 <kmer_size> <hash_functions> <false_positive_rate> <number_of_long_reads_to_generate>

./query.sh data/reference.txt data/longreads.txt 0.05 18 100 0.01 5

./query.sh data/reference.txt data/longreads.txt 0.05 20 200 0.02 10

Sample output:

References:

• Paper on Containment Min Hash approach: https://www.biorxiv.org/content/biorxiv/early/2017/09/04/184150.full.pdf
• Paper's github repo: https://github.com/dkoslicki/MinHashMetagenomics
• Mining Massive Data sets: http://infolab.stanford.edu/~ullman/mmds/ch3.pdf
• Hash Functions generation https://www.eecs.harvard.edu/~michaelm/postscripts/rsa2008.pdf
• Bloom filter http://www.partow.net/programming/bloomfilter/index.html
• Bloom filter https://archive.codeplex.com/?p=libbloom
• Murmur Hash3 https://github.com/aappleby/smhasher
• Mapping reads http://sfg.stanford.edu/mapping.html
• C++ notes: https://www.uow.edu.au/~lukes/TEXTBOOK/notes-cpp/