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cfChIP-seek run

1. About

The cfChIP-seek executable is composed of several inter-related sub commands. Please see cfChIP-seek -h for all available options.

This part of the documentation describes options and concepts for cfChIP-seek run sub command in more detail. With minimal configuration, the run sub command enables you to start running cfChIP-seek pipeline.

Setting up the cfChIP-seek pipeline is fast and easy! In its most basic form, cfChIP-seek run only has three required inputs.

2. Synopsis

$ cfChIP-seek run [--help] \
      [--dry-run] [--job-name JOB_NAME] [--mode {slurm,local}] \
      [--sif-cache SIF_CACHE] [--singularity-cache SINGULARITY_CACHE] \
      [--silent] [--threads THREADS] [--tmp-dir TMP_DIR] \
      [--contrasts CONTRASTS] \
      --input INPUT [INPUT ...] \
      --output OUTPUT \
      --peakcall PEAKCALL

The synopsis for each command shows its arguments and their usage. Optional arguments are shown in square brackets.

A user must provide a list of FastQ (globbing is supported) to analyze via --input argument and an output directory to store results via --output argument, and a peakcall file to pair ChIP and Input samples and define groups of samples.

Use you can always use the -h option for information on a specific command.

2.1 Required arguments

Each of the following arguments are required. Failure to provide a required argument will result in a non-zero exit-code.

--input INPUT [INPUT ...]

Input FastQ or BAM file(s).
type: file(s)

One or more FastQ files can be provided. The pipeline does NOT support single-end data. From the command-line, each input file should seperated by a space. Globbing is supported! This makes selecting FastQ files easy. Input FastQ files should always be gzipp-ed.

Example: --input .tests/*.R?.fastq.gz

--output OUTPUT

Path to an output directory.
type: path

This location is where the pipeline will create all of its output files, also known as the pipeline's working directory. If the provided output directory does not exist, it will be created automatically.

Example: --output /data/$USER/cfChIP-seek_out

--peakcall PEAKCALL

Peakcall file.
type: file

This tab delimited (TSV) file is used to pair each ChIP sample to its corresponding input sample and to assign any groups that are associated with said sample. Please note that multiple groups can be assigned to a given sample using a comma. Group information is used to setup comparsions within groups of samples. This file consists of three columns containing the name of each ChIP sample, the name of each Input sample, and the name of any of its groups. The header of this file needs to be ChIP for the chips column, Input for the inputs column, and Group for the groups column. The base name of each sample should be listed in the ChIP and Input columns. The base name of a given sample can be determined by removing its file extension from the sample's R1 FastQ file, example: WT_S4.R1.fastq.gz becomes WT_S4 in the peakcall file.

Contents of example peakcalls file: 

ChIP  Input   Group
WT_S1 IN_S1   G1,G3
WT_S2 IN_S2   G1,G3
WT_S3 IN_S3   G1
WT_S4 IN_S4   G2,G4
WT_S5 IN_S5   G2,G4
WT_S6 IN_S6   G2
Example: --peakcall /data/$USER/peakcall.tsv

2.2 Analysis options

Each of the following arguments are optional, and do not need to be provided.

2.2.1 Differential Binding

--contrasts CONTRASTS

Contrasts file.
type: file

This tab delimited (TSV) file is used to setup comparisons within different groups of samples. Please see the --peakcall option above for more information about how to define groups within a set of samples. This file consists of two columns containing the names of two groups to compare. The names defined in this file must also exist in the peakcall file.

Please note: the ordering of groups is preserved when creating contrasts. This is important because it dicates how to interpret the direction of the fold-change for your comparison. In the example below, the first comparison can be interpreted as G2 vs. G1. This would result in the following contrast: G2-G1. Within the context of differential binding analysis, a positive fold-change would indicate that the G2 group has higher levels of binding at X region.

Contents of example contrasts file:

G2    G1
G4    G1
G4    G3
Example: --contrasts /data/$USER/contrasts.tsv

2.3 Orchestration options

Each of the following arguments are optional, and do not need to be provided.

--dry-run

Dry run the pipeline.
type: boolean flag

Displays what steps in the pipeline remain or will be run. Does not execute anything!

Example: --dry-run

--silent

Silence standard output.
type: boolean flag

Reduces the amount of information directed to standard output when submitting master job to the job scheduler. Only the job id of the master job is returned.

Example: --silent

--mode {slurm,local}

Execution Method.
type: string
default: slurm

Execution Method. Defines the mode or method of execution. Vaild mode options include: slurm or local.

slurm
The slurm execution method will submit jobs to the SLURM workload manager. It is recommended running cfChIP-seek in this mode as execution will be significantly faster in a distributed environment. This is the default mode of execution.

local
Local executions will run serially on compute instance. This is useful for testing, debugging, or when a users does not have access to a high performance computing environment. If this option is not provided, it will default to a local execution mode.

Example: --mode slurm

--job-name JOB_NAME

Set the name of the pipeline's master job.
type: string default: pl:cfChIP-seek

When submitting the pipeline to a job scheduler, like SLURM, this option always you to set the name of the pipeline's master job. By default, the name of the pipeline's master job is set to "pl:cfChIP-seek".

Example: --job-name pl_id-42

--singularity-cache SINGULARITY_CACHE

Overrides the $SINGULARITY_CACHEDIR environment variable.
type: path
default: --output OUTPUT/.singularity

Singularity will cache image layers pulled from remote registries. This ultimately speeds up the process of pull an image from DockerHub if an image layer already exists in the singularity cache directory. By default, the cache is set to the value provided to the --output argument. Please note that this cache cannot be shared across users. Singularity strictly enforces you own the cache directory and will return a non-zero exit code if you do not own the cache directory! See the --sif-cache option to create a shareable resource.

Example: --singularity-cache /data/$USER/.singularity

--sif-cache SIF_CACHE

Path where a local cache of SIFs are stored.
type: path

Uses a local cache of SIFs on the filesystem. This SIF cache can be shared across users if permissions are set correctly. If a SIF does not exist in the SIF cache, the image will be pulled from Dockerhub and a warning message will be displayed. The cfChIP-seek cache subcommand can be used to create a local SIF cache. Please see cfChIP-seek cache for more information. This command is extremely useful for avoiding DockerHub pull rate limits. It also remove any potential errors that could occur due to network issues or DockerHub being temporarily unavailable. We recommend running cfChIP-seek with this option when ever possible.

Example: --singularity-cache /data/$USER/SIFs

--threads THREADS

Max number of threads for each process.
type: int
default: 2

Max number of threads for each process. This option is more applicable when running the pipeline with --mode local. It is recommended setting this vaule to the maximum number of CPUs available on the host machine.

Example: --threads 12

--tmp-dir TMP_DIR

Max number of threads for each process.
type: path
default: /lscratch/$SLURM_JOBID

Path on the file system for writing temporary output files. By default, the temporary directory is set to '/lscratch/$SLURM_JOBID' for backwards compatibility with the NIH's Biowulf cluster; however, if you are running the pipeline on another cluster, this option will need to be specified. Ideally, this path should point to a dedicated location on the filesystem for writing tmp files. On many systems, this location is set to somewhere in /scratch. If you need to inject a variable into this string that should NOT be expanded, please quote this options value in single quotes.

Example: --tmp-dir /scratch/$USER/

2.4 Miscellaneous options

Each of the following arguments are optional, and do not need to be provided.

-h, --help

Display Help.
type: boolean flag

Shows command's synopsis, help message, and an example command

Example: --help

3. Example

# Step 1.) Grab an interactive node,
# do not run on head node!
srun -N 1 -n 1 --time=1:00:00 --mem=8gb  --cpus-per-task=2 --pty bash
module purge
module load singularity snakemake

# Step 2A.) Dry-run the pipeline
./cfChIP-seek run --input .tests/*.R?.fastq.gz \
                  --output /data/$USER/output \
                  --peakcall .tests/peakcall.tsv \
                  --mode slurm \
                  --dry-run

# Step 2B.) Run the cfChIP-seek pipeline
# The slurm mode will submit jobs to 
# the cluster. It is recommended running 
# the pipeline in this mode.
./cfChIP-seek run --input .tests/*.R?.fastq.gz \
                  --output /data/$USER/output \
                  --peakcall .tests/peakcall.tsv \
                  --mode slurm
Last update: 2024-02-07
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