Join command

usage: ctx31 join [options] <out.ctx> [offset:]in1.ctx[:1,2,4-5] [in2.ctx ...]
  Merge cortex graphs.

  Options:
   -m <mem>            Memory to use
   -n <kmers>          Number of hash table entries (e.g. 1G ~ 1 billion)
   --ncols <c>         How many colours to load at once [default: 1]
   --overlap           Merge corresponding colours from each graph file
   --flatten           Dump into a single colour graph
   --intersect <a.ctx> Only load the kmers that are in graph A.ctx. Can be
     specified multiple times. <a.ctx> is NOT merged into the output file.

  Files can be specified with specific colours: samples.ctx:2,3
  Offset specifies where to load the first colour: 3:samples.c

You can specify to only load some of the colours of a graph using the <in.ctx>:<col> syntax. Colours are numbered from 0 and <col> must be one of: single number; comma separated list of ranges; '*' symbol meaning `all'. The following are all valid examples:

in.ctx
in.ctx:*  (same as above)
in.ctx:0
in.ctx:1,4
in.ctx:9,1-4,3,12  (i.e. 9,1,2,3,4,3,12)

You can specify which colour to start loading into using the :<in.ctx> syntax. In this case <into> must be a single number if it is specified. If it is empty, the next empty colour is used.