add nextflow d30e48d

nextflow/docs/snippets/groupby-size.nf

@@ -0,0 +1,13 @@
+channel.of(
+        tuple('chr1', ['/path/to/region1_chr1.vcf', '/path/to/region2_chr1.vcf']),
+        tuple('chr2', ['/path/to/region1_chr2.vcf', '/path/to/region2_chr2.vcf', '/path/to/region3_chr2.vcf']),
+    )
+    .flatMap { chr, vcfs ->
+        vcfs.collect { vcf ->
+            tuple(chr, vcfs.size(), vcf)    // preserve group size
+        }
+    }
+    .view { v -> "scattered: ${v}" }
+    .groupBy()
+    .map { key, values -> tuple(key, values.toSorted()) }
+    .view { v -> "gathered: ${v}" }