checkmag

#! /usr/bin/ruby

require 'optparse'

default_mag = 0.5
header = 'ion            s       p       d     mag'
  
options = {}
optparse = OptionParser.new do |opts|
  executable_name = File.basename($PROGRAM_NAME)
  opts.banner = "Outputs ion magnetization data from a VASP OUTCAR file\n  
  Usage: #{executable_name} [options] outcar_name\n\n"
  
  opts.on( '-m', '--mag NUM', Float, "Set magnetization cutoff (default = #{default_mag})" ) do |mag|
    options[:mag] = mag
  end
  
  opts.on( '-v', '--verbose', 'Output all ions' ) do
    options[:verbose] = true
  end
  
  opts.on( '-s', '--steps', 'Output data for every step' ) do
    options[:steps] = true
  end
  
  opts.on( '-h', '--help', 'Display this screen' ) do
    puts opts
    exit
  end
end
optparse.parse!

mag = options[:mag] ||= default_mag # magnetization cutoff
filename = ARGV[0] ||= 'OUTCAR'

begin
  outcar = File.open( filename, 'r' ).readlines
rescue
  abort("Could not find file \"#{filename}\"")
end

nions = outcar.grep(/NIONS =\s+([0-9]+)/){$1}[0].to_i
line_no = []
outcar.each_with_index{ |line, index| line_no << index+4 if line =~ /\A magnetization/ }
abort("Could not find magnetization data in file \"#{filename}\"") if line_no.empty?

line_no = [line_no[-1]] unless options[:steps]

line_no.each_with_index do |this_line_no, step|
  if options[:verbose] then
    output = outcar[this_line_no...this_line_no+nions]
  else
    output = outcar[this_line_no...this_line_no+nions].collect{ |line| line if line.strip.split(/\s+/)[4].to_f.abs >= mag }.compact
  end

  puts "\n\# #{step+1}" if options[:steps]
  puts header,'-'*header.length, output
end