# grid.DLapply

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##### Modify the Grid Display List

Call a function on each element of the current display list.

Keywords
dplot
##### Usage
grid.DLapply(FUN, ...)
##### Arguments
FUN

A function; the first argument to this function is passed each element of the display list.

Further arguments to pass to FUN .

##### Details

This function is insanely dangerous (for the grid display list).

Two token efforts are made to try to avoid ending up with complete garbage on the display list:

1. The display list is only replaced once all new elements have been generated (so an error during generation does not result in a half-finished display list).

2. All new elements must be either NULL or inherit from the class of the element that they are replacing.

##### Value

The side effect of these functions is usually to modify the grid display list.

library(grid) # NOT RUN { grid.newpage() grid.rect(width=.4, height=.4, x=.25, y=.75, gp=gpar(fill="black"), name="r1") grid.rect(width=.4, height=.4, x=.5, y=.5, gp=gpar(fill="grey"), name="r2") grid.rect(width=.4, height=.4, x=.75, y=.25, gp=gpar(fill="white"), name="r3") grid.DLapply(function(x) { if (is.grob(x)) x\$gp <- gpar(); x }) grid.refresh() # }