shiny: renderPrint – R documentation

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renderPrint

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 environment in which to evaluate `expr`. For expert use only.
`quoted`	Is `expr` a quoted expression (with `quote()`)? This is useful if you want to save an expression in a variable.
`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

Web Application Framework for R

v1.6.0

GPL-3 | file LICENSE

Authors

Winston Chang [aut, cre], Joe Cheng [aut], JJ Allaire [aut], Carson Sievert [aut], Barret Schloerke [aut], Yihui Xie [aut], Jeff Allen [aut], Jonathan McPherson [aut], Alan Dipert [aut], Barbara Borges [aut], RStudio [cph], jQuery Foundation [cph] (jQuery library and jQuery UI library), jQuery contributors [ctb, cph] (jQuery library; authors listed in inst/www/shared/jquery-AUTHORS.txt), jQuery UI contributors [ctb, cph] (jQuery UI library; authors listed in inst/www/shared/jqueryui/AUTHORS.txt), Mark Otto [ctb] (Bootstrap library), Jacob Thornton [ctb] (Bootstrap library), Bootstrap contributors [ctb] (Bootstrap library), Twitter, Inc [cph] (Bootstrap library), Prem Nawaz Khan [ctb] (Bootstrap accessibility plugin), Victor Tsaran [ctb] (Bootstrap accessibility plugin), Dennis Lembree [ctb] (Bootstrap accessibility plugin), Srinivasu Chakravarthula [ctb] (Bootstrap accessibility plugin), Cathy O'Connor [ctb] (Bootstrap accessibility plugin), PayPal, Inc [cph] (Bootstrap accessibility plugin), Stefan Petre [ctb, cph] (Bootstrap-datepicker library), Andrew Rowls [ctb, cph] (Bootstrap-datepicker library), Dave Gandy [ctb, cph] (Font-Awesome font), Brian Reavis [ctb, cph] (selectize.js library), Salmen Bejaoui [ctb, cph] (selectize-plugin-a11y library), Denis Ineshin [ctb, cph] (ion.rangeSlider library), Sami Samhuri [ctb, cph] (Javascript strftime library), SpryMedia Limited [ctb, cph] (DataTables library), John Fraser [ctb, cph] (showdown.js library), John Gruber [ctb, cph] (showdown.js library), Ivan Sagalaev [ctb, cph] (highlight.js library), R Core Team [ctb, cph] (tar implementation from R)

Initial release