Geo3x3.vim

geo3x3.vim

fu Geo3x3_encode(lat, lng, level)
  let lng = a:lng
  if lng >= 0.0
    let result = "E"
  else
    let result = "W"
    lng += 180.0
  en
  let lat = a:lat + 90.0
  let unit = 180.0
  for i in range(1, a:level - 1)
    let unit /= 3
    let x = float2nr(lng / unit)
    let y = float2nr(lat / unit)
    let n = x + y * 3 + 1
    let result = result . n
    let lng -= x * unit
    let lat -= y * unit
  endfor
  return result
endf

fu Geo3x3_decode(code)
  let code = a:code
  let clen = strlen(code)
  if clen > 0
    let flg = code[0] == "W"
    let unit = 180.0
    let lat = 0.0
    let lng = 0.0
    let level = 1
    for i in range(1, clen)
      let n = float2nr(str2float(code[i]))
      if n == 0
        break
      en
      let unit = unit / 3
      let n = n - 1
      let lng = lng + float2nr(n % 3) * unit
      let lat = lat + float2nr(n / 3) * unit
      let level = level + 1
    endfor
    if flg
      let lng = lng - 180.0
    en
    let lat = lat + unit / 2
    let lng = lng + unit / 2
    let lat = lat - 90
    return [lat, lng, level, unit]
  en
endf