Class: NCVar

Inherits:
NCObject show all
Includes:
NC
Defined in:
lib/io/netcdf.rb

Constant Summary collapse

TYPENAME = 
{
  NC_CHAR   => "char",
  NC_BYTE   => "byte",
  NC_SHORT  => "short",
  NC_INT    => "int",
  NC_FLOAT  => "float",
  NC_DOUBLE => "double",
}
TIME_UNITS = 
{
  "day"     => 86400,
  "days"    => 86400,
  "d"       => 86400,
  "hour"    => 3600,
  "hours"   => 3600,
  "hr"      => 3600,
  "h"       => 3600,
  "minute"  => 60,
  "minutes" => 60,
  "min"     => 60,
  "second"  => 1,
  "seconds" => 1,
  "sec"     => 1,
  "s"       => 1,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from NC

nc_decode, nc_put_att_simple, nc_put_var_all

Methods inherited from NCObject

#attribute, #get_attributes, #get_attributes!

Constructor Details

#initialize(ncfile, var_id) ⇒ NCVar

Returns a new instance of NCVar.



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# File 'lib/io/netcdf.rb', line 98

def initialize (ncfile, var_id)
  @ncfile     = ncfile
  @file_id    = ncfile.file_id
  @var_id     = var_id
  @name       = nc_inq_varname(@file_id, var_id)
  @vartype    = nc_inq_vartype(@file_id, var_id)
  @dims       = ncfile.dims.values_at(*nc_inq_vardimid(@file_id, var_id))
  @shape      = @dims.map{|d| d.len}
  @attributes = get_attributes(@file_id, var_id)
  @dims.freeze
  @shape.freeze
  @attributes.freeze
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(id, *argv) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 321

def method_missing (id, *argv)
  to_ca.send(id, *argv)
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Returns the value of attribute attributes.



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# File 'lib/io/netcdf.rb', line 112

def attributes
  @attributes
end

#dims ⇒ Object (readonly)

Returns the value of attribute dims.



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# File 'lib/io/netcdf.rb', line 112

def dims
  @dims
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/io/netcdf.rb', line 112

def name
  @name
end

Instance Method Details

#[](*argv) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 211

def [] (*argv)
  return get!(*argv)
end

#decode(value) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 140

def decode (value)
  if @attributes.has_key?("_FillValue")
    fill_value = @attributes["_FillValue"]
    case value
    when CArray
      value[:eq, fill_value] = UNDEF
    else
      value = UNDEF if value == fill_value
    end
  end
  if @attributes.has_key?("missing_value")
    missing_values = [@attributes["missing_value"]].flatten
    missing_values.each do |mv|
      case value
      when CArray
        value[:eq, mv] = UNDEF
      else
        if value == mv
          value = UNDEF 
          break
        end
      end
    end
  end
  if @attributes.has_key?("scale_factor")
    value *= @attributes["scale_factor"]
  end
  if @attributes.has_key?("add_offset")
    value += @attributes["add_offset"]
  end
  return value    
end

#definition ⇒ Object 



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# File 'lib/io/netcdf.rb', line 114

def definition
  defs = { "type" => TYPENAME[@vartype] }
  if not dims.empty?
    defs["dim"] = dims.map{|x| x.name }
  end
  atts = {}
  get_attributes!(@file_id, @var_id).each do |k,v|
    atts[k] = NCFile.convert_attribute_value(v)
  end
  defs.update(atts)
  return defs
end

#get(*argv) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 215

def get (*argv)
  if argv.size > 0 and argv[0].is_a?(Struct::CAIndexInfo)
    info = argv.shift
  else
    info = CArray.scan_index(@shape, argv)
  end
  out  = nil
  case info.type
  when CA_REG_ADDRESS
    addr  = info.index[0]
    index = []
    (0..@shape.size-1).reverse_each do |i|
      index[i] = addr % @shape[i]
      addr /= @shape[i]
    end
    out = get_var1(*index)
  when CA_REG_FLATTEN
    out = get_var[nil]
  when CA_REG_POINT
    out = get_var1(*info.index)
  when CA_REG_ALL
    out = get_var()
  when CA_REG_BLOCK
    use_compact = false
    start = []
    count = []
    stride = []
    info.index.each do |idx|
      case idx
      when Array
        start << idx[0]
        count << idx[1]
        stride << idx[2]
      else
        use_compact = true
        start << idx
        count << 1
        stride << 1
      end
    end
    if stride.all?{|x| x == 1 }
      out = get_vara(start, count)
    else
      out = get_vars(start, count, stride)
    end
    if use_compact and out.is_a?(CArray)
      out = out.compact
    end
  when CA_REG_SELECT, CA_REG_GRID
    out = get_var[*argv]
  else
    raise "invalid index"
  end
  return out
end

#get!(*argv) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 271

def get! (*argv)
  info = CArray.scan_index(@shape, argv)
  case info.type
  when CA_REG_METHOD_CALL
    return decode(get_var)[*argv]
  else
    return decode(get(info, *argv))
  end
end

#get_var ⇒ Object 



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# File 'lib/io/netcdf.rb', line 289

def get_var ()
  return nc_get_var(@file_id, @var_id)
end

#get_var! ⇒ Object 



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# File 'lib/io/netcdf.rb', line 293

def get_var! ()
  return decode(nc_get_var(@file_id, @var_id))
end

#get_var1(*index) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 281

def get_var1 (*index)
  return nc_get_var1(@file_id, @var_id, index)
end

#get_var1!(*index) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 285

def get_var1! (*index)
  return decode(get_var1(*index))
end

#get_vara(start, count) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 297

def get_vara (start, count)
  return nc_get_vara(@file_id, @var_id, start, count)
end

#get_vara!(start, count) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 301

def get_vara! (start, count)
  return decode(nc_get_vara(@file_id, @var_id, start, count))
end

#get_varm(start, count, stride, imap) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 313

def get_varm (start, count, stride, imap)
  return nc_get_varm(@file_id, @var_id, start, count, stride, imap)
end

#get_varm!(start, count, stride, imap) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 317

def get_varm! (start, count, stride, imap)
  return decode(nc_get_varm(@file_id, @var_id, start, count, stride, imap))
end

#get_vars(start, count, stride) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 305

def get_vars (start, count, stride)
  return nc_get_vars(@file_id, @var_id, start, count, stride)
end

#get_vars!(start, count, stride) ⇒ Object 



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# File 'lib/io/netcdf.rb', line 309

def get_vars! (start, count, stride)
  return decode(nc_get_vars(@file_id, @var_id, start, count, stride))
end

#inspect ⇒ Object 



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# File 'lib/io/netcdf.rb', line 127

def inspect
  return "#{@name}#{@dims}"
end

#is_dim? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/io/netcdf.rb', line 131

def is_dim? 
  begin
    nc_inq_dimlen(@file_id, @var_id)
    return true
  rescue RuntimeError
    return false
  end
end

#to_ca ⇒ Object 



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# File 'lib/io/netcdf.rb', line 173

def to_ca
  return self[]
end

#to_time ⇒ Object 



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# File 'lib/io/netcdf.rb', line 194

def to_time

  if not @attributes.has_key?("units")
    raise "variable #{@name} has no attribute 'units'"
  elsif @attributes["units"] =~ /\A(.+?)\s+since\s+(.+)\Z/
    interval = TIME_UNITS[$1]
    basetime = Time.parse($2)
    if interval
      return self[].convert(:object) {|x| basetime + interval*x }
    else
      raise "#{$1} is invalid for time units"        
    end
  else
    raise "format of #{@name}:units is not valid for time"
  end
end