gvis Methods

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Print and plot gvis objects

Methods to print and plot gvis objects

Keywords
print, iplot , methods
Usage
"print"(x, tag=NULL, file = "", ...) "plot"(x, tag=NULL,...)
Arguments
x
An object of class gvis, or a HTML file in case of plot.gvis.
tag
Default NULL. Name tag of the objects to be extracted from a gvis object. If tag is missing then the values of getOption("gvis.print.tag"), getOption("gvis.plot.tag") will be used for print.gvis and plot.gvis respectively.

A complete list of available tags is given by the command getOption("gvis.tags").

The default value of gvis.print.tag is "html", which means print.gvis will show a complete web page with the visualisation, while the tag "chart" will present the code for the visualisation chart only. For more information see the details section.

The default tag for plot.gvis.tag is NULL, which will result in R opening a browser window, while any tag which is not NULL will give the same behaviour as print.gvis, e.g. tag='chart' or setting options(gvis.plot.tag='chart') will produce the same output as print(x, tag='chart'). This behaviour is particular helpful when googleVis is used in scripts, like knitr or R.rsp. The plot commands can be used initially in an interactive mode and with one change in options() produce the HTML output required for a programmatic run of the script. See the example section below for a knitr case study.

plot.gvis ignores the argument tag it x is a HTML file name.

file
file name. If "" (the default), output will be printed to the standard output connection, the console unless redirected by sink.
...
arguments passed on to cat (print.gvis) or browseURL (plot.gvis).
Details

An object of class "gvis" is a list containing at least the following components (tags):

type
Google visualisation type, e.g. 'MotionChart'

chartid
character id of the chart object. Unique chart ids are required to place several charts on the same page.

html
a list with the building blocks for a page
header
a character string of a html page header: ...,

chart
a named character vector of the chart's building blocks:
jsHeader
Opening .

jsChart
Call of the jsDisplayChart function.

divChart
container to embed the chart into the page.

caption
character string of a standard caption, including data name and chart id.
footer
character string of a html page footer: ..., including the used R and googleVis version and link to Google's Terms of Use.

Value

print.gvis
None (invisible NULL).
plot.gvis
Returns the file name invisibly.

Note

The plot command does not open a graphics device in the traditional way. Instead it creates HTML files in a temporary directory and uses the R HTTP server to display the output of a googleVis function locally. A browser with Flash and Internet connection is required. The displayed page includes a link (click on the chart id) to a further page, which shows the code of the chart for the user to copy and paste into her own page.

References

Please see also the package vignette for the usage of the googleVis package with RApache, brew, knitr and R.rsp.

See Also

See also cat, browseURL, createGoogleGadget and gvisMerge for combining charts.

Aliases
  • print.gvis
  • plot.gvis
Examples
## Show gvis options
sapply(c("gvis.print.tag", "gvis.plot.tag", "gvis.tags"), getOption)

M <- gvisMotionChart(Fruits, "Fruit", "Year")
str(M)
## The output for a complete web page
M

## Access only the plot,
M$html$chart

## wrap it in cat and it becomes more readable,
cat(unlist(M$html$chart))

## or use the print function.
print(M, tag="chart")

## Extract the data as a JavaScript function.
print(M, tag="jsData")

## Display the visualisation.
## A web browser with Internet connection and Flash is required.
plot(M)

## Combine with another chart, e.g. table
#tbl <- gvisTable(Fruits, options=list(height=220))
#Mtbl <- gvisMerge(M, tbl)
#plot(Mtbl)


## Example of using googleVis with knitr and markdown

## Not run: 
# ## Simple knitr/markdown file with googleVis
# knitrRmd <-"
# # Markdown example with knitr and googleVis
# ===========================================
# This is a little Markdown example file.
# Set the googleVis options first.
# In this case change the behaviour of plot.gvis
# ```{r setOptions, message=FALSE}
# library(googleVis)
# op <- options(gvis.plot.tag='chart')
# ```
# The following plot statements will automatically return  the HTML
# required for the 'knitted' output. 
# 
# ## Combo chart
# ```{r ComboExample, results='asis', tidy=FALSE}
# ## Add the mean
# CityPopularity$Mean=mean(CityPopularity$Popularity)
# CC <- gvisComboChart(CityPopularity, xvar='City',
#           yvar=c('Mean', 'Popularity'),
#           options=list(seriesType='bars',
#                        width=450, height=300,
#                        title='City Popularity',
#                        series='{0: {type:\"line\"}}'))
# plot(CC)
# ```
# Example of gvisComboChart with R code shown above.
# 
# ## Place two charts next to each other
# ```{r gvisMergeExample, results='asis', echo=FALSE}
# Geo <- gvisGeoChart(Exports, locationvar='Country', colorvar='Profit', 
#                     options=list(height=300, width=350)) 
# Tbl <- gvisTable(Exports, options=list(height=300, width=200))
# plot(gvisMerge(Geo, Tbl, horizontal=TRUE))
# ``````
# Example of a gvisGeoChart with gvisTable and R code hidden.
# 
# ## Motion Chart
# ```{r MotionChartExample, results='asis', tidy=FALSE}
# M <- gvisMotionChart(Fruits, 'Fruit', 'Year',
#          options=list(width=400, height=350))
# plot(M)
# ```
# Please note that the Motion Chart is only displayed when hosted on a
# web server, or is placed in a directory which has been added to the 
# trusted sources in the [security settings of Macromedia]
# (http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager04.html). 
# See the googleVis package vignette for more details. 
# 
# ```{r resetOptions}
# ## Set options back to original options
# options(op)
# ```
# "
# 
# ## Write the content of knitrRmd into a Rmd-file, knit it and convert it
# ## into a html output. Finally show the file with the R-help http
# ## server, this will ensure that also the motion chart is visible.
# 
# library(knitr)
# library(markdown)
# 
# wd <- getwd()
# setwd(tempdir())
# fn=tempfile()
# fn.Rmd <- paste(fn, ".Rmd", sep="")
# fn.md <- paste(fn, ".md", sep="")
# fn.html <- paste(fn, "-out.html", sep="") 
# ## Write R Markdown into a file
# cat(knitrRmd, file=fn.Rmd)
# render_markdown()
# knit(fn.Rmd, fn.md)
# knit2html(fn.md)
# 
# ## Open output in browser
# ## Use plot.gvis which will use the R-help http server
# ## The URL will start with http://127.0.0.1...
# ## The HTML file will be copied into a temporary directory
# plot.gvis(fn.html)
# ## Compare to browseURL, its URL will start with file://... the motion
# ## chart is unlikely to be displayed because of Flash security
# ## settings. See the googleVis vignette for more details. 
# browseURL(fn.html)
# setwd(wd)
# ## End(Not run)

## Not run: 
# ## Updating the data of an existing googleVis web page
# 
# ## Suppose you have an existing web page in which you embedded a
# ## motion chart with the id "mtnc".
# ## Now you have a new set of data, but you would like to avoid
# ## touching the html file again.
# ## The idea is to write the data and JavaScript functions into separate
# ## files and to refer to these in the html page.
# 
# ## In this example we call the chart id "mtnc"
# ## To display the example we use the R HTTP server again, and
# ## write the files into a temp directory
# 
# myChartID <- "mtnc"
# ## baseURL should reflect your web address, e.g. http://myHomePage.com
# baseURL <- sprintf("http://127.0.0.1:%s/custom/googleVis", tools:::httpdPort)
# wwwdir <- tempdir() ## the www repository on your computer
# 
#   
# ## Create a motion chart
# M=gvisMotionChart(Fruits, "Fruit", "Year", chartid=myChartID)
# 
# ## Here is our plot again
# plot(M)
# 
# ## Write the data and functions into separate files:
# cat(M$html$chart['jsData'], file=file.path(wwwdir, "gvisData.js"))
# cat(M$html$chart[c('jsDrawChart', 'jsDisplayChart', 'jsChart')], 
# 			    file=file.path(wwwdir, "gvisFunctions.js"))
# 
#   
# ## Create a html page with reference to the above
# ## JavaScript files
#   
# html <- sprintf('
# <html>
#   <head>
#   <script type="text/javascript" src="http://www.google.com/jsapi">
#   </script>
#   <script type="text/javascript" src="%s/gvisFunctions.js"></script>
#   <script type="text/javascript" src="%s/gvisData.js"></script>
#   <script type="text/javascript">
#   displayChart%s()
#   </script>
#   </head>
#   <body>
#   <div id="%s" style="width: 600px; height: 500px;"></div>
#   </body>
#   </html>
#   ', baseURL, baseURL, myChartID, myChartID)
#   
# ## Write html scaffold into a file
# cat(html, file=file.path(wwwdir, paste("Chart", myChartID, ".html", sep="")))
# 
# ## Display the result via
# URL <- paste(baseURL,"/Chart", myChartID, ".html", sep="")
# browseURL(URL)
# 
# ## Update the data, say the data should have shown North and South
# ## instead of East and West as a location  
# FruitsUpdate <- Fruits
# levels(FruitsUpdate$Location)=c("North", "South")
# 
# Mupdate=gvisMotionChart(FruitsUpdate, "Fruit", "Year", chartid=myChartID)
# 
# ## Only update the file gvisData.js:
# cat(Mupdate$html$chart['jsData'], file=file.path(wwwdir, "gvisData.js"))
# 
# ## Redisplay the chart with the updated data
# browseURL(URL)
# 
# ## End(Not run)
Documentation reproduced from package googleVis, version 0.6.0, License: GPL (>= 2)

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