How to emit grouped collectFile result as a tuple

[ray1919]

The following code group chunked file tuples into merged files, however the sample val is lost at last, how to preserve merged file with id val as a tuple just like inputed?

process pfam_homology_chunk {                                                      
    input:                                                                      
    tuple val(sample), file(orfPepSplit) from orfPepSplit                       
                                                                                
    output:                                                                     
    tuple val(sample), "*.domtblout" into pfamOutSplit                          
                                                                                
    """                                                                         
    hmmscan --cpu 2 \\                                                          
        --domtblout ${orfPepSplit}.domtblout \\                                 
        ${params.pfam_db} \\                                                    
        $orfPepSplit                                                            
    """                                                                         
}

pfamOutSplit                                                                   
    .groupTuple(by: 0)                                                             
    .collectFile(name: 'merged.domblout', sort: { it[0] } , newLine: false) { it[1] }
    .view()  

At the same time, I found the merged file by collectFile was not renamed to 'merged.domblout'. The return path show that all chunks was merged into one of the chunked .domtblout file. It puzzled me a lot.

[ray1919]

I solve this problem by just merge all grouped file in a single process like cat *.xxx > $sample.xxx.