Error with multiMap

[hkaspersen]

Hello!
I am trying to implement a multiMap for my input channel by splitting a csv input file and running multiMap (similar to what nf-core does), like this:

def criteria = multiMapCriteria {
            id, R1, R2, NP ->
                shortreads: R1 != 'NA' ? tuple(tuple(id, [R1, R2])) : null
                longreads: NP != 'NA' ? tuple(id, NP) : null
        }
Channel
        .fromPath(params.input, checkIfExists: true)
        .splitCsv(header:true, sep:",")
        .multiMap (criteria)
        .set { input_ch }

However, I cannot seem to make it work. This is the error message I am getting:

ERROR ~ Invalid method invocation `doCall` with arguments: [sample:2014-01-5792-1-1-4-1, R1:/cluster/projects/nn9305k/active/hkaspersen/Projects/ONT_PMQR/rawdata/illumina/199-2014-01-5792_CGTACTAG-CCTAGAGT_concat_R1_001.fastq.gz, R2:/cluster/projects/nn9305k/active/hkaspersen/Projects/ONT_PMQR/rawdata/illumina/199-2014-01-5792_CGTACTAG-CCTAGAGT_concat_R2_001.fastq.gz, NP:/cluster/projects/nn9305k/active/hkaspersen/Projects/ONT_PMQR/rawdata/nanopore/2014-01-5792-1-1-4-1.radar1.fastq.gz] (java.util.LinkedHashMap) on _closure5 type

 -- Check '.nextflow.log' file for details
Pipeline execution stopped with the following message: No signature of method: Script_1f7ed10f91178354$_runScript_closure1$_closure2$_closure3$_closure5.doCall() is applicable for argument types: (LinkedHashMap) values: [[sample:2014-01-5792-1-1-4-1, R1:/cluster/projects/nn9305k/active/hkaspersen/Projects/ONT_PMQR/rawdata/illumina/199-2014-01-5792_CGTACTAG-CCTAGAGT_concat_R1_001.fastq.gz, ...]]
Possible solutions: doCall(java.lang.Object, java.lang.Object, java.lang.Object, java.lang.Object), findAll(), findAll(), isCase(java.lang.Object), isCase(java.lang.Object)

I am not familiar with this error message, and I do not know whether the error is related to the multiMapping or something else. Any help would be greatly appreciated!

[bentsherman]

I think the problem is that splitCsv is passing a map to the multiMap when it should be a list. You can set header to false or insert a map operator after the splitCsv:

.map { row -> [row.id, row.R1, row.R2, row.NP] }

[hkaspersen]

This worked perfectly, thanks!