renderPrint: Text Output

In shiny: Web Application Framework for R

Text Output

Description

renderPrint() prints the result of expr, while renderText() pastes it together into a single string. renderPrint() is equivalent to print(); renderText() is equivalent to cat(). Both functions capture all other printed output generated while evaluating expr.

renderPrint() is usually paired with verbatimTextOutput(); renderText() is usually paired with textOutput().

Usage

renderPrint(
  expr,
  env = parent.frame(),
  quoted = FALSE,
  width = getOption("width"),
  outputArgs = list()
)

renderText(
  expr,
  env = parent.frame(),
  quoted = FALSE,
  outputArgs = list(),
  sep = " "
)

Arguments

expr	An expression to evaluate.
env	The parent environment for the reactive expression. By default, this is the calling environment, the same as when defining an ordinary non-reactive expression. If expr is a quosure and quoted is TRUE, then env is ignored.
quoted	If it is TRUE, then the quote()ed value of expr will be used when expr is evaluated. If expr is a quosure and you would like to use its expression as a value for expr, then you must set quoted to TRUE.
width	Width of printed output.
outputArgs	A list of arguments to be passed through to the implicit call to verbatimTextOutput() or textOutput() when the functions are used in an interactive RMarkdown document.
sep	A separator passed to cat to be appended after each element.

Details

The corresponding HTML output tag can be anything (though pre is recommended if you need a monospace font and whitespace preserved) and should have the CSS class name shiny-text-output.

Value

For renderPrint(), note the given expression returns NULL then NULL will actually be visible in the output. To display nothing, make your function return invisible().

Examples

isolate({

# renderPrint captures any print output, converts it to a string, and
# returns it
visFun <- renderPrint({ "foo" })
visFun()
# '[1] "foo"'

invisFun <- renderPrint({ invisible("foo") })
invisFun()
# ''

multiprintFun <- renderPrint({
  print("foo");
  "bar"
})
multiprintFun()
# '[1] "foo"\n[1] "bar"'

nullFun <- renderPrint({ NULL })
nullFun()
# 'NULL'

invisNullFun <- renderPrint({ invisible(NULL) })
invisNullFun()
# ''

vecFun <- renderPrint({ 1:5 })
vecFun()
# '[1] 1 2 3 4 5'


# Contrast with renderText, which takes the value returned from the function
# and uses cat() to convert it to a string
visFun <- renderText({ "foo" })
visFun()
# 'foo'

invisFun <- renderText({ invisible("foo") })
invisFun()
# 'foo'

multiprintFun <- renderText({
  print("foo");
  "bar"
})
multiprintFun()
# 'bar'

nullFun <- renderText({ NULL })
nullFun()
# ''

invisNullFun <- renderText({ invisible(NULL) })
invisNullFun()
# ''

vecFun <- renderText({ 1:5 })
vecFun()
# '1 2 3 4 5'

})

shiny documentation built on Nov. 18, 2023, 1:08 a.m.