methods (version 3.6.2)

show: Show an Object

Description

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).

Usage

show(object)

Arguments

object

Any R object

Value

show returns an invisible NULL.

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.

See Also

showMethods prints all the methods for one or more functions.

Examples

# NOT RUN {
## following the example shown in the setMethod documentation ...
setClass("track", slots = c(x="numeric", y="numeric"))
setClass("trackCurve", contains = "track", slots = c(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
# }
# 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
# }