# cf.relpath

`cf.``relpath`(filename, start=None)

  Return a relative filepath to a file.

  The filepath is relative either from the current directory or from an optional start point.

  If a string containing URL is provided then it is returned unchanged.

  See also

  `cf.abspath`, `cf.dirname`, `cf.pathjoin`

  Parameters: | filename: `str` The name of the file. start: `str`, optional The start point for the relative path. By default the current directoty is used.
  Returns: | out: `str` The relative path.
  Examples: |

      >>> cf.relpath('/data/archive/file.nc')
      '../file.nc'
      >>> cf.relpath('/data/archive///file.nc', start='/data')
      'archive/file.nc'
      >>> cf.relpath('http://data/archive/file.nc')
      'http://data/archive/file.nc'