tuple nextflow

Hi !

I’m a newbie nextflow user, i can’t understand the operating mode of “tuple val(sample)”.

Does it create two channels and use two channels ? so we can use it only if we have two files comming from previous channel ?

Thank you !

a tuple is used when the Channel contains more than one value.

"tuple val(sample)" with only one value ‘sample’ looks strange to me….

for example if a channel contains 3 columns

+-------+-----------+----------------------+
| chrom | size      | fileName             |
+-------+-----------+----------------------+
| chr1  | 249250621 | /gbdb/hg19/hg19.2bit |
| chr2  | 243199373 | /gbdb/hg19/hg19.2bit |
| chr3  | 198022430 | /gbdb/hg19/hg19.2bit |
| chr4  | 191154276 | /gbdb/hg19/hg19.2bit |
| chr5  | 180915260 | /gbdb/hg19/hg19.2bit |
| chr6  | 171115067 | /gbdb/hg19/hg19.2bit |
| chr7  | 159138663 | /gbdb/hg19/hg19.2bit |
| chrX  | 155270560 | /gbdb/hg19/hg19.2bit |
| chr8  | 146364022 | /gbdb/hg19/hg19.2bit |
| chr9  | 141213431 | /gbdb/hg19/hg19.2bit |
+-------+-----------+----------------------+

a process would look like:

process test {
input:
    tuple chrom,chromLen,bitPath from my_input_channel
output:
   tuple chrom,path("output.txt") into test_out
script:
"""
ls -lah '${bitPath}' > output.txt
"""
}