These functions are methods for the generic commands
  print,
  predict and
  plot 
  for the class "rho2hat".
An object of class "rho2hat" is an estimate
  of the intensity of a point process, as a function of two
  given spatial covariates. See rho2hat.
  
The method plot.rho2hat displays the estimated function
  \(\rho\) using plot.fv, and optionally
  adds a rug plot of the observed values of the covariate.
  In this plot the two axes represent possible values of the two covariates.
The method predict.rho2hat computes a pixel image of the
  intensity \(\rho(Z_1(u), Z_2(u))\)
  at each spatial location \(u\), where \(Z_1(u)\)
  and \(Z_2(u)\) are the two spatial covariates.