## What is this?

A ruby library to manipulate Fortran namelists

## How to use

```ruby
  require './lib/nml'
  
  # parse an existing namelist
  nml = NML_Reader.read(nml_file)

  # returns a hash of hashes with group names
  # as keys of the second level of hashes
  # namelist groups can be retrieved by
  # referencing these keys
    # get namelist group '&share'

   share = nml[:share]

   # the return value is of type NV, which is
   # a Hash extended with the methods <<, del
   # and keep

   # <<(args) merges args with the first key
   # of the reciever hash

   # keep(*args) returns a new NV object which
   # only contains the variables indicated through
   # args array

     share=share.keep(:wrf_core, :max_dom, :start_date)

   # del(*args) deletes specified variables of
   # a particular group

     share=share.del(:wrf_core, :max_dom)

   # After manipulating namelist groups, write them
   # to a new namelist
   # Step 1 -  Create a new Namelist Group
     # create a namelist group 'share'

       nshare = NML_Group.create(:share)
  
     # add group variables, these can be new hashes
     # or modified NV hashes from the previous manipulation

       nshare << share 
       nshare << {:a => 1} 

    # << operations can be nested
      nshare << share << {:a => 1}

  # Step 2 - Construct a new namelist
    # Push namelist groups to NML_Writer using instance_method <<

    nml_writer = NML_Writer.new

    nml_writer << nshare << ngrid << ungrib << nmet

    # optionally re-order group names by passing in
    # an array of keys in desired order

       # example retrieves group names from original
       # namelist and reverses the order
       # make sure all group names are included in
       # the array; otherwise it won't sort the output

        nml_writer.okeys=nml[:okeys].reverse # reverse the
                                             # order of group
                                             # names in output

    # Write out to STDOUT

    nml_writer >> STDOUT
   
    # Write to a file or other object supporting puts
    outfile = File.new("namelist.wps.asia","w")
    nml_writer >> outfile
    outfile.close
```

Enjoy!

Copyright Saji Hameed (2012)  [email protected]