# ![nf-core/methylseq](docs/images/nf-core-methylseq_logo_light.png#gh-light-mode-only) ![nf-core/methylseq](docs/images/nf-core-methylseq_logo_dark.png#gh-dark-mode-only)

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## Introduction

**nf-core/methylseq** is a bioinformatics analysis pipeline used for Methylation (Bisulfite) sequencing data. It pre-processes raw data from FastQ inputs, aligns the reads and performs extensive quality-control on the results.

The pipeline is built using [Nextflow](https://www.nextflow.io), a workflow tool to run tasks across multiple compute infrastructures in a very portable manner. It uses Docker / Singularity containers making installation trivial and results highly reproducible.

On release, automated continuous integration tests run the pipeline on a full-sized dataset on the AWS cloud infrastructure. This ensures that the pipeline runs on AWS, has sensible resource allocation defaults set to run on real-world datasets, and permits the persistent storage of results to benchmark between pipeline releases and other analysis sources.The results obtained from the full-sized test can be viewed on the [nf-core website](https://nf-co.re/methylseq/results).

## Pipeline Summary

The pipeline allows you to choose between running either [Bismark](https://github.com/FelixKrueger/Bismark) or [bwa-meth](https://github.com/brentp/bwa-meth) / [MethylDackel](https://github.com/dpryan79/methyldackel).
Choose between workflows by using `--aligner bismark` (default, uses bowtie2 for alignment), `--aligner bismark_hisat` or `--aligner bwameth`.

| Step                                         | Bismark workflow | bwa-meth workflow     |
| -------------------------------------------- | ---------------- | --------------------- |
| Generate Reference Genome Index _(optional)_ | Bismark          | bwa-meth              |
| Merge re-sequenced FastQ files               | cat              | cat                   |
| Raw data QC                                  | FastQC           | FastQC                |
| Adapter sequence trimming                    | Trim Galore!     | Trim Galore!          |
| Align Reads                                  | Bismark          | bwa-meth              |
| Deduplicate Alignments                       | Bismark          | Picard MarkDuplicates |
| Extract methylation calls                    | Bismark          | MethylDackel          |
| Sample report                                | Bismark          | -                     |
| Summary Report                               | Bismark          | -                     |
| Alignment QC                                 | Qualimap         | Qualimap              |
| Sample complexity                            | Preseq           | Preseq                |
| Project Report                               | MultiQC          | MultiQC               |

## Usage

> **Note**
> If you are new to Nextflow and nf-core, please refer to [this page](https://nf-co.re/docs/usage/installation) on how
> to set-up Nextflow. Make sure to [test your setup](https://nf-co.re/docs/usage/introduction#how-to-run-a-pipeline)
> with `-profile test` before running the workflow on actual data.

First, prepare a samplesheet with your input data that looks as follows:

`samplesheet.csv`:

```csv
sample,fastq_1,fastq_2
SRR389222_sub1,https://github.com/nf-core/test-datasets/raw/methylseq/testdata/SRR389222_sub1.fastq.gz
SRR389222_sub2,https://github.com/nf-core/test-datasets/raw/methylseq/testdata/SRR389222_sub2.fastq.gz
SRR389222_sub2,https://github.com/nf-core/test-datasets/raw/methylseq/testdata/SRR389222_sub3.fastq.gz
Ecoli_10K_methylated,https://github.com/nf-core/test-datasets/raw/methylseq/testdata/Ecoli_10K_methylated_R1.fastq.gz,https://github.com/nf-core/test-datasets/raw/methylseq/testdata/Ecoli_10K_methylated_R2.fastq.gz
```

Each row represents a fastq file (single-end) or a pair of fastq files (paired end).

Now, you can run the pipeline using:

```bash
nextflow run nf-core/methylseq --input samplesheet.csv --outdir <OUTDIR> --genome GRCh37 -profile <docker/singularity/podman/shifter/charliecloud/conda/institute>
```

> **Warning:**
> Please provide pipeline parameters via the CLI or Nextflow `-params-file` option. Custom config files including those
> provided by the `-c` Nextflow option can be used to provide any configuration _**except for parameters**_;
> see [docs](https://nf-co.re/usage/configuration#custom-configuration-files).

For more details, please refer to the [usage documentation](https://nf-co.re/methylseq/usage) and the [parameter documentation](https://nf-co.re/methylseq/parameters).

## Pipeline output

To see the the results of a test run with a full size dataset refer to the [results](https://nf-co.re/methylseq/results) tab on the nf-core website pipeline page.
For more details about the output files and reports, please refer to the
[output documentation](https://nf-co.re/methylseq/output).

## Credits

These scripts were originally written for use at the [National Genomics Infrastructure](https://portal.scilifelab.se/genomics/) at [SciLifeLab](http://www.scilifelab.se/) in Stockholm, Sweden.

- Main author:
  - Phil Ewels ([@ewels](https://github.com/ewels/))
- Contributors:
  - Rickard Hammarén ([@Hammarn](https://github.com/Hammarn/))
  - Alexander Peltzer ([@apeltzer](https://github.com/apeltzer/))
  - Patrick Hüther ([@phue](https://github.com/phue/))

## Contributions and Support

If you would like to contribute to this pipeline, please see the [contributing guidelines](.github/CONTRIBUTING.md).

For further information or help, don't hesitate to get in touch on the [Slack `#methylseq` channel](https://nfcore.slack.com/channels/methylseq) (you can join with [this invite](https://nf-co.re/join/slack)).

## Citations

If you use nf-core/methylseq for your analysis, please cite it using the following doi: [10.5281/zenodo.1343417](https://doi.org/10.5281/zenodo.1343417)

An extensive list of references for the tools used by the pipeline can be found in the [`CITATIONS.md`](CITATIONS.md) file.

You can cite the `nf-core` publication as follows:

> **The nf-core framework for community-curated bioinformatics pipelines.**
>
> Philip Ewels, Alexander Peltzer, Sven Fillinger, Harshil Patel, Johannes Alneberg, Andreas Wilm, Maxime Ulysse Garcia, Paolo Di Tommaso & Sven Nahnsen.
>
> _Nat Biotechnol._ 2020 Feb 13. doi: [10.1038/s41587-020-0439-x](https://dx.doi.org/10.1038/s41587-020-0439-x).
