gvisScatterChart define series dynamically

问题:

I am dynamically creating a couple of gvisScatterCharts. I want to define the colors of each line, which I can do using series and the color attribute. There is nothing like an order or a fix number by which I can predefine the colors. So I want to create an array of attributes parallel to my colors and just place it at series=myColors.

The problem is that gVis expects a string like:

   series="[{color: 'black', visibleInLegend: false}]", 

As soon as I create a string using the paste function gVis doesn't accept them any more and just shows a blank page as chart. (Even when marking the " using \")

Is this a bug or am I doing something wrong?

回答1:

This is not a bug, just as said in the help it expects a JSON string so you need to build JSON string.

Using RJSONIO you can build the JSON option using toJSON

library(googleVis)
library(RJSONIO)
myColor <- 'grey'   ## my dynamic color, here I fix but you can read it ,e.g
                    ## from a chart config file or whatever you want
isLegend <- TRUE    ## a boolean value 

myseriesOptions <- toJSON(list(list(color=myColor),list(visibleInLegend=isLegend)))

For example

Scatter2 <- gvisScatterChart(women, 
                             options=list(legend="none",
                                          lineWidth=2, pointSize=0,
                                          title="Women", vAxis="{title:'weight (lbs)'}",
                                          hAxis="{title:'height (in)'}", 
                                          width=300, height=300,
                                          series = myseriesOptions    ))

 plot(Scatter2)

PS : We can use fromJSON to get the R form of the string to construct, e.g

fromJSON("{title:'mytitle'}")        ## the ouptut is a list 
$itl
NULL

cat(toJSON(list(title='mytitle')))   ## I construct my list and I use toJSON
                                     ## I get my origin json form

{
 "title": "mytitle" 
}