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Google Word Tree with R wordtree gvisWordTree

Source: R/gvisWordTree.R
gvisWordTree.Rd

A word tree depicts multiple parallel sequences of words. It could be used to show which words most often follow or precede a target word (e.g., "Cats are...") or to show a hierarchy of terms (e.g., a decision tree).

Usage

gvisWordTree(
  data,
  textvar = "",
  sizevar = "",
  stylevar = "",
  idvar = "",
  parentvar = "",
  options = list(),
  method = "implicit",
  chartid
)

Arguments

data

data.frame that contains the data to be visualised

textvar

a string that refers to the column name in data that contains the text to be used.

sizevar

a string that refers to the column name in data that contains the size of the words in the word tree.

stylevar

a string that refers to the column name in data that contains the stlye of the text. For no warning message in plot, should be called <textvar>.style.

idvar

(only when format is explicit) a string that refers to the column name in data that contains the unique ID of the text.

parentvar

(only when format is explicit) a string that refers to the column name in data that contains the ID of the parent of the text.

options

list of configuration options, see:

https://developers.google.com/chart/interactive/docs/gallery/wordtree#Configuration_Options

The parameters can be set via a named list. The parameters have to map those of the Google documentation.

  • Boolean arguments are set to either TRUE or FALSE, using the R syntax.

  • Google API parameters with a single value and with names that don't include a "." are set like one would do in R, that is options=list(width=200, height=300). Exceptions to this rule are the width and height options for gvisAnnotatedTimeLine and gvisAnnotationChart. For those two functions, width and height must be character strings of the format "Xpx", where X is a number, or "automatic". For example, options=list(width="200px", height="300px").

  • Google API parameters with names that don't include a ".", but require multivalues are set as a character, wrapped in "[ ]" and separated by commas, e.g. options=list(colors="['#cbb69d', '#603913', '#c69c6e']")

  • Google API parameters with names that do include a "." present parameters with several sub-options and have to be set as a character wrapped in " ". The values of those sub-options are set via parameter:value. Boolean values have to be stated as 'true' or 'false'. For example the Google documentaion states the formating options for the vertical axis and states the parameter as vAxis.format. Then this paramter can be set in R as:options=list(vAxis="{format:'#,###%'}").

  • If several sub-options have to be set, e.g. titleTextStyle.color, titleTextStyle.fontName and titleTextStyle.fontSize, then those can be combined in one list item such as:options=list(titleTextStyle="{color:'red', fontName:'Courier', fontSize:16}")

  • paramters that can have more than one value per sub-options are wrapped in "[ ]". For example to set the labels for left and right axes use:options=list(vAxes="[{title:'val1'}, {title:'val2'}]")

  • gvis.editor a character label for an on-page button that opens an in-page dialog box enabling users to edit, change and customise the chart. By default no value is given and therefore no button is displayed.

For more details see the Google API documentation and the R examples below.
method

a string to say whether the word tree is either:

  • implicit - will weight and connect automatically, or

  • explicit - can specify weights and connections

chartid

character. If missing (default) a random chart id will be generated based on chart type and tempfile

Value

gvisWordTree returns list of class

"gvis" and "list". An object of class "gvis" is a list containing at least the following components:

type

Google visualisation type

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: <html>...<body>,

chart

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

jsHeader

Opening <script> tag and reference to Google's JavaScript library.

jsData

JavaScript function defining the input data as a JSON object.

jsDrawChart

JavaScript function combing the data with the visualisation API and user options.

jsDisplayChart

JavaScript function calling the handler to display the chart.

jsFooter

End tag </script>.

jsChart

Call of the jsDisplayChart function.

divChart

<div> 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: </body>...</html>, including the used R and googleVis version and link to Google's Terms of Use.

Warning

The word tree chart may be undergoing substantial revisions in future Google Charts releases.

References

Google Chart Tools API: https://developers.google.com/chart/interactive/docs/gallery/wordtree

Author

Ashley Baldry

Examples

## Please note that by default the googleVis plot command
## will open a browser window and requires Internet
## connection to display the visualisation.

wt1 <- gvisWordTree(Cats, textvar = "Phrase")
plot(wt1)

Cats2 <- Cats
Cats2$Phrase.style <- ifelse(Cats$Sentiment >= 7, "green", 
                             ifelse(Cats$Sentiment <= 3, "red", "black"))
                             
wt2 <- gvisWordTree(Cats2, textvar = "Phrase", stylevar = "Phrase.style",
                    options = list(fontName = "Times-Roman",
                                   wordtree = "{word: 'cats'}",
                                   backgroundColor = "#cba"))
plot(wt2)

# Explicit word tree
exp.data <- data.frame(id = as.numeric(0:9),
                       label = letters[1:10],
                       parent = c(-1, 0, 0, 0, 2, 2, 4, 6, 1, 7),
                       size = c(10, 5, 3, 2, 2, 2, 1, 1, 5, 1),
                       stringsAsFactors = FALSE)

wt3 <- gvisWordTree(exp.data, idvar = "id", textvar = "label", 
                    parentvar = "parent", sizevar = "size",
                    options = list(wordtree = "{format: 'explicit'}"),
                    method = "explicit")
plot(wt3)