gnu parallel - How do I denote that arguments are related? -

i have following arguments chr1 chr2 chr3, + - , 2 3.

for every chr want have + , 2 once , - , 3 once, this:

parallel --whatflags-to-use?? echo {} {} {} ::: + - ::: 2 3 ::: chr1 chr2 chr3 + 2 chr1 + 2 chr2 + 2 chr3 - 3 chr1 - 3 chr2 - 3 chr3 

the closest have gotten this:

parallel --xapply echo {} {} {} ::: + - ::: 2 3 ::: chr1 chr2 chr3 + 2 chr1 + 2 chr3 - 3 chr2 

how do this? not see how in brilliant tutorial, perhaps not possible...

parallel echo {} ::: '+ 2' '- 3' ::: chr1 chr2 chr3 

if need arguments split, bit harder: want 1 argument depend on another:

parallel echo strand='{=1 $_=$_==2?"+":"-"=}' read={1} chrom={2} ::: 2 3 ::: chr1 chr2 chr3 

alternatively:

parallel --xapply echo str={1} read={2} chrom={3}  ::: + - ::: 2 3 ::: chr{1,1,2,2,3,3} parallel --colsep ' ' echo str={1} read={2} chrom={3}  ::: '+ 2' '- 3' ::: chr{1..3}