renderText: Text Output

In tomkuipers1402/shiny: Web Application Framework for R

Description

Makes a reactive version of the given function that also uses base::cat() to turn its result into a single-element character vector.

Usage

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

Arguments

expr	An expression that returns an R object that can be used as an argument to cat.
env	The environment in which to evaluate expr.
quoted	Is expr a quoted expression (with quote())? This is useful if you want to save an expression in a variable.
outputArgs	A list of arguments to be passed through to the implicit call to textOutput() when renderText is used in an interactive R Markdown 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.

The result of executing func will passed to cat, inside a utils::capture.output() call.

See Also

renderPrint() for capturing the print output of a function, rather than the returned text value.

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'

})

tomkuipers1402/shiny documentation built on Feb. 13, 2020, 7:22 p.m.