Module: GeoUnits::Converter::Dms

Extended by:
Dms
Includes:
NumericCheckExt
Included in:
Dms
Defined in:
lib/geo_units/converter/dms.rb

Defined Under Namespace

Classes: ParseError

Instance Method Summary collapse

Instance Method Details

#parse_dms(dms_str, options = {}) ⇒ Object

Raises:



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# File 'lib/geo_units/converter/dms.rb', line 11

def parse_dms dms_str, options= {}
  # check for signed decimal degrees without NSEW, if so return it directly
  return dms_str if is_numeric?(dms_str)

  raise ParseError, "DMS parse error: #{dms_str}" if !(dms_str =~ /[NSEW]$/) || (dms_str =~ /\./)

  # strip off any sign or compass dir'n & split out separate d/m/s
  dms = dms_str.strip.gsub(/^-/,'').gsub(/[NSEW]$/i,'').split(/[^0-9.,]+/).map(&:strip).map(&:to_f)
  return nil if dms.empty?

  # and convert to decimal degrees...
  deg = case dms.length
  when 3 # interpret 3-part result as d/m/s
    dms[0]/1 + dms[1]/60 + dms[2]/3600
  when 2 # interpret 2-part result as d/m
    dms[0]/1 + dms[1]/60
  when 1 # just d (possibly decimal) or non-separated dddmmss
    d = dms[0];
    # check for fixed-width unseparated format eg 0033709W
    d = "0#{d}" if (/[NS]/i.match(dms_str)) # - normalise N/S to 3-digit degrees
    d = "#{d.slice(0,3)/1}#{deg.slice(3,5)/60}#{deg.slice(5)/3600}" if (/[0-9]{7}/.match(deg)) 
    d
  else
    nil
  end

  raise ParseError, "DMS parse error: #{deg} for #{dms_str}" if !deg

  deg = (deg * -1) if (/^-|[WS]$/i.match(dms_str.strip)) # take '-', west and south as -ve
  deg.to_f
end

#to_dms(deg, format = :dms, dp = nil) ⇒ Object

Convert decimal degrees to deg/min/sec format

- degree, prime, double-prime symbols are added, but sign is discarded, though no compass
  direction is added

Parameters:

  • deg: (Number) —

    Degrees

  • [format=dms]: (String) —

    Return value as ‘d’, ‘dm’, ‘dms’

  • [dp=0|2|4]: (Number) —

    No of decimal places to use - default 0 for dms, 2 for dm, 4 for d



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# File 'lib/geo_units/converter/dms.rb', line 54

def to_dms deg, format = :dms, dp = nil 
  deg = begin
    deg.to_f
  rescue
    nil
  end
  return nil if !deg # give up here if we can't make a number from deg   

  # default values
  format ||= :dms
  dp = if dp.nil?
    case format.to_sym
    when :d 
      4
    when :dm 
      2
    else
      0 # default
    end
  end
  dp ||= 0

  deg = deg.abs # (unsigned result ready for appending compass dir'n)

  case format
  when :d
    d = deg.round(dp)       # round degrees
    ds = "0#{d}" if (d <100)    # pad with leading zeros
    ds = "0#{ds}" if (d <10) 
    dms = ds.to_s.concats("\u00B0")  # add º symbol
  when :dm
    min = (deg*60).round(dp)   # convert degrees to minutes & round
    d = d.to_i
    d = (min / 60).floor          # get component deg/min
    m = (min % 60).round(dp)   # pad with trailing zeros
    ds = d
    ms = m
    ds = "0#{d}" if (d<100)        # pad with leading zeros
    ds = "0#{d}" if (d<10)
    ms = "0#{m}" if (m<10)
    dms = ds.to_s.concats("\u00B0", ms, "\u2032") # add º, ' symbols
  when :dms
    sec = (deg * 3600).round   # convert degrees to seconds & round
    d = (sec / 3600).floor          # get component deg/min/sec
    m = ((sec / 60) % 60).floor
    s = (sec % 60).round(dp)     # pad with trailing zeros
    ds = d
    ms = m
    ss = s
    ds = "0#{d}" if (d < 100)          # pad with leading zeros
    ds = "0#{ds}" if (d < 10) 
    ms = "0#{m}" if (m < 10) 
    ss = "0#{s}" if (s < 10) 
    dms = ds.to_s.concats("\u00B0", ms, "\u2032", ss, "\u2033")  # add º, ', " symbols
  end
  return dms
end