FastSK- Fast Sequence Analysis with Gapped String Kernels

Title: FastSK: Fast Sequence Analysis with Gapped String Kernels

Paper BioArxivVersion

GitHub: https://github.com/QData/FastSK

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Abstract

Gapped k-mer kernels with Support Vector Machines (gkm-SVMs) have achieved strong predictive performance on regulatory DNA sequences on modestly-sized training sets. However, existing gkm-SVM algorithms suffer from the slow kernel computation time, as they depend exponentially on the sub-sequence feature-length, number of mismatch positions, and the task’s alphabet size. In this work, we introduce a fast and scalable algorithm for calculating gapped k-mer string kernels. Our method, named FastSK, uses a simplified kernel formulation that decomposes the kernel calculation into a set of independent counting operations over the possible mismatch positions. This simplified decomposition allows us to devise a fast Monte Carlo approximation that rapidly converges. FastSK can scale to much greater feature lengths, allows us to consider more mismatches, and is performant on a variety of sequence analysis tasks. On 10 DNA transcription factor binding site (TFBS) prediction datasets, FastSK consistently matches or outperforms the state-of-the-art gkmSVM-2.0 algorithms in AUC, while achieving average speedups in kernel computation of 100 times and speedups of 800 times for large feature lengths. We further show that FastSK outperforms character-level recurrent and convolutional neural networks across all 10 TFBS tasks. We then extend FastSK to 7 English medical named entity recognition datasets and 10 protein remote homology detection datasets. FastSK consistently matches or outperforms these baselines. Our algorithm is available as a Python package and as C++ source code. (Available for download at https://github.com/Qdata/FastSK/. Install with the command make or pip install)

Citations

@article {Blakely2020.04.21.053975,
	author = {Blakely, Derrick and Collins, Eamon and Singh, Ritambhara and Qi, Yanjun},
	title = {FastSK: Fast Sequence Analysis with Gapped String Kernels},
	elocation-id = {2020.04.21.053975},
	year = {2020},
	doi = {10.1101/2020.04.21.053975},
	publisher = {Cold Spring Harbor Laboratory},
	URL = {https://www.biorxiv.org/content/early/2020/04/23/2020.04.21.053975},
	eprint = {https://www.biorxiv.org/content/early/2020/04/23/2020.04.21.053975.full.pdf},
	journal = {bioRxiv}
}

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