Run samples through PEPPRO using Looper

This guide walks you through extending PEPPRO to run on multiple samples using looper. The pipeline can be run directly from the command line for a single sample (see Install and run). If you need to run it on many samples, you could write your own sample handling code, but we have pre-configured everything to work nicely with looper, our sample handling engine.

1: Install looper

Looper is a pipeline submission engine that makes it easy to deploy any pipeline across samples. It will let you run the jobs locally, in containers, using any cluster resource manager, or in containers on a cluster.

You can install looper using pip:

pip install --user loopercli

2: Run an example through looper

Start by running the example project (peppro_test.yaml) in the examples/meta/ folder. Let's use looper's -d argument to do a dry run, which will create job scripts for every sample in a project, but will not execute them:

cd peppro
looper run -d examples/meta/peppro_test.yaml

If the looper executable is not in your $PATH, add the following line to your .bashrc or .profile:

export PATH=$PATH:~/.local/bin

If that worked, let's actually run the example by taking out the -d flag:

looper run examples/meta/peppro_test.yaml

There are lots of other cool things you can do with looper, like dry runs, summarize results, check on pipeline run status, clean intermediate files to save disk space, lump multiple samples into one job, and more. For details, consult the looper docs.

3: Configure your project files

To run your own samples, you'll need to organize them in PEP format, which is explained in how to create a PEP and is universal to all pipelines that read PEPs, including PEPPRO. To get you started, there are examples you can adapt in the examples/ folder (e.g. example test PEP). In short, you need two files for your project:

  1. project config file -- describes output locations, pointers to data, etc.
  2. sample annotation file -- comma-separated value (CSV) list of your samples.

The sample annotation file must specify these columns:

  • sample_name
  • library ('PRO' or 'PROSEQ' or 'PRO-seq')
  • organism (e.g. 'human' or 'mouse')
  • read1
  • read2 (if paired)
  • whatever else you want