
334 Spatial Point Patterns: Methodology and Applications with R
> fitgrad <- update(fitcsr, .
~
grad)
To modif y the right-hand side of the formula, use ‘.’ on the right-hand sid e, modifying it with the
model operators:
> fitall <- update(fitgrad, .
~
. + elev)
> fitall
Nonstationary Poisson process
Log intensity:
~
grad + elev
Estimate S.E. CI95.lo CI95.hi Ztest Zval
(Intercept) -8.55862 0.341101 -9.22717 -7.89008 *** -25.091
grad 5.84104 0.255861 5.33956 6.34252 *** 22.829
elev 0.02141 0.002288 0.01693 0.02589 *** 9.358
To remove the intercept, use -1 or +0:
> fitp <- update(fitall, .
~
. - 1)
The symbolic manipulation of for mulae involving the symbol ‘.’ is ...