parameters: (self, xpos=0)
return_statement: return ip, op, err
docstring: Select sounding at a specific position or by number.
  
          Retrieve inphase, outphase and error(if exist) vector from index
          or near given position
  
          Returns:
              IP : array
              OP : array
              ERR : array or None (if no error is specified)
docstring_summary: Select sounding at a specific position or by number.
docstring_tokens: Select sounding at a specific position or by number .
function: def selectData(self, xpos=0):
          """Select sounding at a specific position or by number.
  
          Retrieve inphase, outphase and error(if exist) vector from index
          or near given position
  
          Returns:
              IP : array
              OP : array
              ERR : array or None (if no error is specified)
          """
          # check for index
          if isinstance(xpos, int) and (xpos < len(self.x)) and (xpos >= 0):
              n = xpos
          else:
              n = np.argmin(np.absolute(self.x - xpos))
  
          ip = self.IP[n, self.activeFreq]
          op = self.OP[n, self.activeFreq]
          err = None
          if self.ERR is not None:
              err = self.ERR[n, self.activeFreq]
  
          return ip, op, err
function_tokens: def selectData ( self , xpos = 0 ) : # check for index if isinstance ( xpos , int ) and ( xpos < len ( self . x ) ) and ( xpos >= 0 ) : n = xpos else : n = np . argmin ( np . absolute ( self . x - xpos ) ) ip = self . IP [ n , self . activeFreq ] op = self . OP [ n , self . activeFreq ] err = None if self . ERR is not None : err = self . ERR [ n , self . activeFreq ] return ip , op , err