The overall problem I'm trying to solve is a way to count the number of reads present in each file at every step of a QC pipeline I'm building. I have a shell script I've used in the past which takes in a directory and outputs the number of reads per file. Since I'm looking to use a directory as input, I tried following the format laid out by Rasmus in this post:
https://bitbucket.org/snakemake/snakemake/issues/961/rule-with-folder-as-input-and-output
Here is some example input created earlier in the pipeline:
$ ls -1 cut_reads/
97_R1_cut.fastq.gz
97_R2_cut.fastq.gz
98_R1_cut.fastq.gz
98_R2_cut.fastq.gz
99_R1_cut.fastq.gz
99_R2_cut.fastq.gz
And a simplified Snakefile to first aggregate all reads by creating symlinks in a new directory, and then use that directory as input for the read counting shell script:
import os
configfile: "config.yaml"
rule all:
input:
"read_counts/read_counts.txt"
rule agg_count:
input:
cut_reads = expand("cut_reads/{sample}_{rdir}_cut.fastq.gz", rdir=["R1", "R2"], sample=config["forward_reads"])
output:
cut_dir = directory("read_counts/cut_reads")
run:
os.makedir(output.cut_dir)
for read in input.cut_reads:
abspath = os.path.abspath(read)
shell("ln -s {abspath} {output.cut_dir}")
rule count_reads:
input:
cut_reads = "read_counts/cut_reads"
output:
"read_counts/read_counts.txt"
shell:
'''
readcounts.sh {input.cut_reads} >> {output}
'''
Everything's fine in the dry-run, but when I try to actually execute it, I get a fairly cryptic error message:
Building DAG of jobs...
Using shell: /bin/bash
Provided cores: 1
Rules claiming more threads will be scaled down.
Job counts:
count jobs
1 agg_count
1 all
1 count_reads
3
[Tue Jun 18 11:31:22 2019]
rule agg_count:
input: cut_reads/99_R1_cut.fastq.gz, cut_reads/98_R1_cut.fastq.gz, cut_reads/97_R1_cut.fastq.gz, cut_reads/99_R2_cut.fastq.gz, cut_reads/98_R2_cut.fastq.gz, cut_reads/97_R2_cut.fastq.gz
output: read_counts/cut_reads
jobid: 2
Job counts:
count jobs
1 agg_count
1
[Tue Jun 18 11:31:22 2019]
Error in rule agg_count:
jobid: 0
output: read_counts/cut_reads
Exiting because a job execution failed. Look above for error message
Shutting down, this might take some time.
Exiting because a job execution failed. Look above for error message
Complete log: /home/douglas/snakemake/scrap_directory/.snakemake/log/2019-06-18T113122.202962.snakemake.log
read_counts/ was created, but there's no cut_reads/ directory inside. No other error messages are present in the complete log. Anyone know what's going wrong or how to receive a more descriptive error message?
I'm also (obviously) fairly new to snakemake, so there might be a better way to go about this whole process. Any help is much appreciated!