docs: def to_array(self, variables):
          """
          Converts the clamping to a 1-D array with respect to the given variables
  
          Parameters
          ----------
          variables : list[str]
              List of variables names
  
  
          Returns
          -------
          `numpy.ndarray`_
              1-D array where position `i` correspond to the sign of the clamped variable at
              position `i` in the given list of variables
  
  
          .. _numpy.ndarray: http://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html#numpy.ndarray
          """
          arr = np.zeros(len(variables), np.int8)
          dc = dict(self)
  
          for i, var in enumerate(variables):
              arr[i] = dc.get(var, arr[i])
  
          return arr