FASTQC

Generate fastq qc statistics using fastqc.

Example

This wrapper can be used in the following way:

rule fastqc:
    input:
        "reads/{sample}.fastq"
    output:
        html="qc/fastqc/{sample}.html",
        zip="qc/fastqc/{sample}_fastqc.zip" # the suffix _fastqc.zip is necessary for multiqc to find the file. If not using multiqc, you are free to choose an arbitrary filename
    params: ""
    log:
        "logs/fastqc/{sample}.log"
    threads: 1
    wrapper:
        "0.72.0/bio/fastqc"

Note that input, output and log file paths can be chosen freely. When running with

snakemake --use-conda

the software dependencies will be automatically deployed into an isolated environment before execution.

Software dependencies

  • fastqc==0.11.9

Input/Output

Input:

  • fastq file

Output:

  • html file containing statistics
  • zip file containing statistics

Authors

  • Julian de Ruiter

Code

"""Snakemake wrapper for fastqc."""

__author__ = "Julian de Ruiter"
__copyright__ = "Copyright 2017, Julian de Ruiter"
__email__ = "julianderuiter@gmail.com"
__license__ = "MIT"


from os import path
from tempfile import TemporaryDirectory

from snakemake.shell import shell

log = snakemake.log_fmt_shell(stdout=False, stderr=True)


def basename_without_ext(file_path):
    """Returns basename of file path, without the file extension."""

    base = path.basename(file_path)

    split_ind = 2 if base.endswith(".fastq.gz") else 1
    base = ".".join(base.split(".")[:-split_ind])

    return base


# Run fastqc, since there can be race conditions if multiple jobs
# use the same fastqc dir, we create a temp dir.
with TemporaryDirectory() as tempdir:
    shell(
        "fastqc {snakemake.params} --quiet -t {snakemake.threads} "
        "--outdir {tempdir:q} {snakemake.input[0]:q}"
        " {log:q}"
    )

    # Move outputs into proper position.
    output_base = basename_without_ext(snakemake.input[0])
    html_path = path.join(tempdir, output_base + "_fastqc.html")
    zip_path = path.join(tempdir, output_base + "_fastqc.zip")

    if snakemake.output.html != html_path:
        shell("mv {html_path:q} {snakemake.output.html:q}")

    if snakemake.output.zip != zip_path:
        shell("mv {zip_path:q} {snakemake.output.zip:q}")