show

Show an Object

Display the object, by printing, plotting or whatever suits its class. This function exists to be specialized by methods. The default method calls showDefault.

Formal methods for show will usually be invoked for automatic printing (see the details).

Keywords
programming
Usage
show(object)
Arguments
object
Any R object
Details

Objects from an S4 class (a class defined by a call to setClass) will be displayed automatically is if by a call to show. S4 objects that occur as attributes of S3 objects will also be displayed in this form; conversely, S3 objects encountered as slots in S4 objects will be printed using the S3 convention, as if by a call to print.

Methods defined for show will only be inherited by simple inheritance, since otherwise the method would not receive the complete, original object, with misleading results. See the simpleInheritanceOnly argument to setGeneric and the discussion in setIs for the general concept.

Value

show returns an invisible NULL.

See Also

showMethods prints all the methods for one or more functions.

Aliases
  • show
  • show-methods
  • show,ANY-method
  • show,traceable-method
  • show,ObjectsWithPackage-method
  • show,MethodDefinition-method
  • show,MethodWithNext-method
  • show,genericFunction-method
  • show,classRepresentation-method
Examples
library(methods) ## following the example shown in the setMethod documentation ... setClass("track", representation(x="numeric", y="numeric")) setClass("trackCurve", representation("track", smooth = "numeric")) t1 <- new("track", x=1:20, y=(1:20)^2) tc1 <- new("trackCurve", t1) setMethod("show", "track", function(object)print(rbind(x = object@x, y=object@y)) ) ## The method will now be used for automatic printing of t1 t1 ## Not run: [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] # x 1 2 3 4 5 6 7 8 9 10 11 12 # y 1 4 9 16 25 36 49 64 81 100 121 144 # [,13] [,14] [,15] [,16] [,17] [,18] [,19] [,20] # x 13 14 15 16 17 18 19 20 # y 169 196 225 256 289 324 361 400 # ## End(Not run) ## and also for tc1, an object of a class that extends "track" tc1 ## Not run: [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] # x 1 2 3 4 5 6 7 8 9 10 11 12 # y 1 4 9 16 25 36 49 64 81 100 121 144 # [,13] [,14] [,15] [,16] [,17] [,18] [,19] [,20] # x 13 14 15 16 17 18 19 20 # y 169 196 225 256 289 324 361 400 # ## End(Not run)
Documentation reproduced from package methods, version 3.3.0, License: Part of R 3.3.0

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