In snakemake I would like to access keys from the config from within the shell: directive. I can use {input.foo}, {output.bar}, and {params.baz}, but {config.quux} is not supported. Is there a way to achieve this?
rule do_something:
input: "source.txt"
output: "target.txt"
params:
# access config[] here. parameter tracking is a side effect
tmpdir = config['tmpdir']
shell:
# using {config.tmpdir} or {config['tmpdir']} here breaks the build
"./scripts/do.sh --tmpdir {params.tmpdir} {input} > {output}; "
I could assign the parts of the config I want to a key under params, and then use a {param.x} replacement, but this has unwanted side effects (e.g. the parameter is saved in the snakemake metadata (i.e. .snakemake/params_tracking). Using run: instead of shell: would be another workaround, but accessing {config.tmpdir} directly from the shell block, would be most desirable.
"./scripts/do.sh --tmpdir {config[tmpdir]} {input} > {output}; "
should work here.
It is stated in the documentation:
http://snakemake.readthedocs.io/en/stable/snakefiles/configuration.html#standard-configuration
"For adding config placeholders into a shell command, Python string formatting syntax requires you to leave out the quotes around the key name, like so:"
shell:
"mycommand {config[foo]} ..."
Related
I would like to do something like the following in Snakemake:
rule RULE:
input: ...
output: "{tool}/{file}"
shell: lambda wildcards: command_for_tool[wildcards.tool]
possibly with the shell command wrapped in a format(.., file=wildcards.file) to expand the {file} that will be inside the command_for_tool.
Currently I can do this using a run: calling shell(..), but I can't use this because I'm benchmarking the memory usage of the rule and going via python adds 30+MB overhead.
It is possible to use some python code inside the shell: rule that returns a string, but in this case I cannot figure out how to use the wildcards.
It is also possible to use wildcards directly in a string value, where they will be substituted automatically, but this doesn't allow for the map-lookup I need.
Is there a clean solution to this? (Currently I'm trying to work around it using params:.) To me it seems like an omission/inconsistency in how snakemake works.
Using your own suggestion, a solution using params seems quite clean:
rule RULE:
input:
'in.txt',
output:
'{foo}.txt',
params:
cmd= lambda wc: command_for_tool[wc.foo],
shell:
"""
{params.cmd}
"""
although I can see that for consistency with the input and params directive, also shell: lambda wildcards: command_for_tool[wildcards.tool] should work.
I am struggling with a very simple thing. On input of my snakemake pipeline I would like to have a directory, list its content, and process each file from that directory in parallel. Naively I thought something like this should work:
rule all:
input:
"in/{test}.txt"
output:
"out/{test}.txt"
shell:
"echo {input} >> {output}"
This ends with the error
WorkflowError:
Target rules may not contain wildcards. Please specify concrete files or a rule without wildcards.
All the resources I could find start with hard-coding the list of jobs in the script, which is something I want to avoid to keep the pipeline generic. The idea is to just point the pipeline to a directory with a list of files and let it do its job. Is this possible? Seems fairly simple and intuitive, but couldn't find an example showing that.
I don't know what command you used for this rule, but the following workflow should suffice your purpose
rule all:
input:
expand("out/{prefix}.txt", prefix=glob_wildcards("in/{test}.txt").test)
rule test:
input:
"in/{test}.txt"
output:
"out/{test}.txt"
shell:
"echo {input} >> {output}"
glob_wildcards is a function by snakemake to find out all the files that match the specified pattern (in/{test}.txt in this case), then .text is to get the list of strings that match {test} in filenames (example: "ab" in "in/ab.txt").
Then expand can fill the string to the placeholder variable that wrapped by curly bracket, then generate a list of input file names.
So rule all wants a list of input files correspond to all txt files in in folder, then it would let snakemake execute rule test for every file
I am currently working on this project where iam struggling with this issue.
My current directory structure is
/shared/dir1/file1.bam
/shared/dir2/file2.bam
/shared/dir3/file3.bam
I want to convert various .bam files to fastq in the results directory
results/file1_1.fastq.gz
results/file1_2.fastq.gz
results/file2_1.fastq.gz
results/file2_2.fastq.gz
results/file3_1.fastq.gz
results/file3_2.fastq.gz
I have the following code:
END=["1","2"]
(dirs, files) = glob_wildcards("/shared/{dir}/{file}.bam")
rule all:
input: expand( "/results/{sample}_{end}.fastq.gz",sample=files, end=END)
rule bam_to_fq:
input: {dir}/{sample}.bam"
output: left="/results/{sample}_1.fastq", right="/results/{sample}_2.fastq"
shell: "/shared/packages/bam2fastq/bam2fastq --force -o /results/{sample}.fastq {input}"
This outputs the following error:
Wildcards in input files cannot be determined from output files:
'dir'
Any help would be appreciated
You're just missing an assignment for "dir" in your input directive of the rule bam_to_fq. In your code, you are trying to get Snakemake to determine "{dir}" from the output of the same rule, because you have it setup as a wildcard. Since it didn't exist, as a variable in your output directive, you received an error.
input:
"{dir}/{sample}.bam"
output:
left="/results/{sample}_1.fastq",
right="/results/{sample}_2.fastq",
Rule of thumb: input and output wildcards must match
rule all:
input:
expand("/results/{sample}_{end}.fastq.gz", sample=files, end=END)
rule bam_to_fq:
input:
expand("{dir}/{{sample}}.bam", dir=dirs)
output:
left="/results/{sample}_1.fastq",
right="/results/{sample}_2.fastq"
shell:
"/shared/packages/bam2fastq/bam2fastq --force -o /results/{sample}.fastq {input}
NOTES
the sample variable in the input directive now requires double {}, because that is how one identifies wildcards in an expand.
dir is no longer a wildcard, it is explicitly set to point to the list of directories determined by the glob_wildcard call and assigned to the variable "dirs" which I am assuming you make earlier in your script, since the assignment of one of the variables is successful already, in your rule all input "sample=files".
I like and recommend easily differentiable variable names. I'm not a huge fan of the usage of variable names "dir", and "dirs". This makes you prone to pedantic spelling errors. Consider changing it to "dirLIST" and "dir"... or anything really. I just fear one day someone will miss an 's' somewhere and it's going to be frustrating to debug. I'm personally guilty, an thus a slight hypocrite, as I do use "sample=samples" in my core Snakefile. It has caused me minor stress, thus why I make this recommendation. Also makes it easier for others to read your code as well.
EDIT 1; Adding to response as I had initially missed the requirement for key-value matching of the dir and sample
I recommend keeping separate the path and the sample name in different variables. Two approaches I can think of:
Keep using glob_wildcards to make a blanket search for all possible variables, and then use a python function to validate which path+file combinations are legit.
Drop the usage of glob_wildcards. Propagate the directory name as a wildcard variable, {dir}, throughout your rules. Just set it as a sub-directory of "results". Use pandas to pass known, key-value pairs listed in a file to the rule all. Initially I suggest generating the key-value pairs file manually, but eventually, it's generation could just be a rule upstream of others.
Generalizing bam_to_fq a little bit... utilizing an external config, something like....
from pandas import read_table
rule all:
input:
expand("/results/{{sample[1][dir]}}/{sample[1][file]}_{end}.fastq.gz", sample=read_table(config["sampleFILE"], " ").iterrows(), end=['1','2'])
rule bam_to_fq:
input:
"{dir}/{sample}.bam"
output:
left="/results/{dir}/{sample}_1.fastq",
right="/results/{dir}/{sample}_2.fastq"
shell:
"/shared/packages/bam2fastq/bam2fastq --force -o /results/{sample}.fastq {input}
sampleFILE
dir file
dir1 file1
dir2 file2
dir3 file3
I'd like to know if there is a way in Snakemake to define a dependency which is actually not an input file.
What I mean by that is that there are programs that expect some files to exists while there are not provided on the command line.
Let's consider bwa as an example.
This is a rule from Johannes Köster mapping rules:
rule bwa_mem_map:
input:
lambda wildcards: config["references"][wildcards.reference],
lambda wildcards: config["units"][wildcards.unit]
output:
"mapping/{reference}/units/{unit}.bam"
params:
sample=lambda wildcards: UNIT_TO_SAMPLE[wildcards.unit],
custom=config.get("params_bwa_mem", "")
log:
"mapping/log/{reference}/{unit}.log"
threads: 8
shell:
"bwa mem {params.custom} "
r"-R '#RG\tID:{wildcards.unit}\t"
"SM:{params.sample}\tPL:{config[platform]}' "
"-t {threads} {input} 2> {log} "
"| samtools view -Sbh - > {output}"
Here, bwa expect that the genome index file exists while it is not a command-line argument (the path to the index file is deduced from the genome path).
Is there a way to tell Snakemake that the index file is a dependency, and Snakemake will look in its rule if he knows how to generate this file ?
I suppose you could still rewrite your rule inputs as:
rule bwa_mem_map:
input:
genome=lambda wildcards: config["references"][wildcards.reference],
fastq=lambda wildcards: config["units"][wildcards.unit]
index=foo.idx
And adapt the rule run part consequently.
Is it the best solution?
Thanks in advance.
Benoist
I think the only way snakemake handles dependencies between rules is through files, so I'd say you are doing it correctly when you put the index file explicitly as an input for your mapping rule, even though this file does not appear in the mapping command.
For what its worth, I do the same for bam index files, which are an implicit dependency for some tools: I put both the sorted bam file and its index as input, but only use the bam file in the shell or run part. And I have a rule generating both having the two files as output.
input and output files do not need to appear in shell / run parts of a rule.
New to snakemake and I've been trying to transform my shell script based pipeline into snakemake based today and run into a lot of syntax issues.. I think most of the trouble I have is around getting all the files in a particular directories and infer output names from input names since that's how I use shell script (for loop), in particular, I tried to use expand function in the output section and it always gave me an error.
After checking some example Snakefile, I realized people never use expand in the output section. So my first question is: is output the only section where expand can't be used and if so, why? What if I want to pass a prefix defined in config.yaml file as part of the output file and that prefix can not be inferred from input file names, how can I achieve that, just like what I did below for the log section where {runid} is my prefix?
Second question about syntax: I tried to pass a user defined id in the configuration file (config.yaml) into the log section and it seems to me that here I have to use expand in the following form, is there a better way of passing strings defined in config.yaml file?
log:
expand("fastq/fastqc/{runid}_fastqc_log.txt",runid=config["run"])
where in the config.yaml
run:
"run123"
Third question: I initially tried the following 2 methods but they gave me errors so does it mean that inside log (probably input and output) section, Python syntax is not followed?
log:
"fastq/fastqc/"+config["run"]+"_fastqc_log.txt"
log:
"fastq/fastqc/{config["run"]}_fastqc_log.txt"
Here is an example of small workflow:
# Sample IDs
SAMPLES = ["sample1", "sample2"]
CONTROL = ["sample1"]
TREATMENT = ["sample2"]
rule all:
input: expand("{treatment}_vs_{control}.bed", treatment=TREATMENT, control=CONTROL)
rule peak_calling:
input: control="{control}.sam", treatment="{treatment}.sam"
output: "{treatment}_vs_{control}.bed"
shell: "touch {output}"
rule mapping:
input: "{samples}.fastq"
output: "{samples}.sam"
shell: "cp {input} {output}"
I used the expand function only in my final target. From there, snakemake can deduce the different values of the wildcards used in the rules "mapping" and "peak_calling".
As for the last part, the right way to put it would be the first one:
log:
"fastq/fastqc/" + config["run"] + "_fastqc_log.txt"
But again, snakemake can deduce it from your target (the rule all, in my example).
rule mapping:
input: "{samples}.fastq"
output: "{samples}.sam"
log: "{samples}.log"
shell: "cp {input} {output}"
Hope this helps!
You can use f-strings:
If this is you folder_with_configs/some_config.yaml:
var: value
Then simply
configfile:
"folder_with_configs/some_config.yaml"
rule one_to_rule_all:
output:
f"results/{config['var']}.file"
shell:
"touch {output[0]}"
Do remember about python rules related to nesting different types of apostrophes.
config in the smake rule is a simple python dictionary.
If you need to use additional variables in a path, e.g. some_param, use more curly brackets.
rule one_to_rule_all:
output:
f"results/{config['var']}.{{some_param}}"
shell:
"touch {output[0]}"
enjoy