How do you return output from R function

Question

I have an R script that reads a csv file and converts to json ouput, here is the script:

output<-function(myname){
  library(rjson)
  setwd("C:/Rstudio/vCenter")
  ##vcenter <- system.file("instvcenter.csv", package = packageName())
  res <- read.csv("vcenter.csv", header = TRUE, sep = ",")
res$Cpu<-as.numeric(round(res$Cpu, digits=3))
res$Time<-as.numeric(res$Time-14400)

servers <- split(res, res$Host)
dumFun <- function(x){
  sData <- servers[x][[1]]
  if(nrow(sData) >0){
    # create appropriate list
    dumList <- unname(apply(sData[,2:3], 1, function(y) unname(as.list(y))))
    return(toJSON(list(name = x, data = dumList))) 
  }
}       
jsData <- lapply(names(servers), dumFun)
jsInd <- sapply(jsData, is.null)

p<-paste(jsData[!jsInd], collapse = ',')
list(
p<-paste('[', p, ']')
)
return(p)

}

this is the javascript that reads the output:

<!DOCTYPE html>
<html>
  <head>
    <title>Hello</title>

    <!-- Include order: first jquery, then opencpu.js, and then your code -->
    <script src="opencpu/jquery-1.10.2.min.js"></script>
    <script src="opencpu/opencpu-0.4.js"></script>
    <script src="opencpu/highcharts.js"></script>
    <script src="opencpu/export-csv.js"></script>

    <script>
    //init this script when the page has loaded
    $(document).ready(function(){
      $("#submitbutton").on("click", function(){
        //disable the button to prevent multiple clicks
        $("#submitbutton").attr("disabled", "disabled");

        var myname = $("#namefield").val();
        //perform the request
        var req = ocpu.rpc("output", {
          myname : myname

        }, function(output){

          //var data=JSON.stringify(output, null, 4);
         //console.log(data);
          //console.log($(this).data("events"));
          //var data=output[0][1];
          //var data =JSON.stringify(output, null, 4);
          //document.write(output);

          //document.write(output[1]);
          //console.log('Error:', output[0][0]);
          //var data = data.replace(/\[1\]/, "");
        $('#output').highcharts({
        //$("#output").highcharts('StockChart',{
        chart: {
            borderColor: '#98AFC7',
                borderRadius: 20,
                borderWidth: 1,
                renderTo: 'output',
                type: 'line',
                marginRight: 10,
                zoomType: 'x',
                resetZoomButton: {
                position: {

                    x: -50,
                    y: -50
                    }
                }
            },
            plotOptions: {
                line: {
                    marker: {
                        radius: 4,
                        lineColor: '#666666',
                        lineWidth: 5
                    }
                }
            },

            exporting: {
            enabled: true
        },
           legend: {
            enabled: true,
            backgroundColor: '#FCFFC5',
            borderColor: 'black',
            borderWidth: 2,
            shadow: true
        },
            rangeSelector: {
                enabled:true               
            },

            scrollbar: {
                    enabled: true
                    },
            navigator : {
                enabled : true
            },
            xAxis: {
        type:'datetime',
                gridLineColor: '#EEEEEE',
                gridLineWidth: 1
            },
            yAxis: { // Primary yAxis
                labels: {

                    style: {
                        color: 'blue'
                    }
                },
                gridLineColor: '#EEEEEE',
                gridLineWidth: 1,

                title: {
                    text: '% CPU Utilization',
                    fontSize: '50px',
                    style: {
                        color: 'blue'
                    }
                }
            },

            credits: {
                enabled: false
            },

            title: {
                text: '% CPU UTILIZATION',
                style: {
                    color: '#333000',
                    fontSize: '14px'
                }
            },


            tooltip: {
            positioner: function(){
                    return{x:20,y:-5};
                },
                pointFormat: '<span style="color:{series.color}">{series.name}</span>: <b>{point.y}<b>',
                valueDecimals: 2
            },

            series: output
    });
});

        //if R returns an error, alert the error message
        req.fail(function(){
          alert("Server error: " + req.responseText);
        });

        //after request complete, re-enable the button 
        req.always(function(){
          $("#submitbutton").removeAttr("disabled")
        });
      });
    });
    </script>

    <style>
      #output{
        height: 600px;
        width: 1500px;
        border: 0px;
        padding: 3px;
      }
    </style>

  </head>

  <body>
    <h1>My First HighStock Chart!!!!</h1>

    <b>Your name: </b> <input type="text" id="namefield">

    <button id="submitbutton" type="button">Submit to server!</button>

    <div id="output"> </div>

    <br />


  </body>
</html>

When I run this script, it gives me an ouput like this:

[1] [ {"name":"rosevengesx02","data":[[1406269800,0.092],[1406271600,0.092]]}]

I tried:

return(cat(p))

but wen I call this function remotely, I get:

[object Object]

How would I return the function so that I dont have [1], in the output?

@RichardScriven, that did not work. I still get [1] at the output. — user1471980
– user1471980, Commented Aug 10, 2014 at 3:30
@RomanLuštrik, I execute a function remotely and I get a json formated data. I verified that I get the data to the front end by doing document.write(output). When I pass that data to highcharts series object, I don't see the lines. I do however see the chart border, title but no data on the chart. I am at a loss, cannot seem to find an answer. — user1471980
– user1471980, Commented Aug 11, 2014 at 1:47
@SebastianBochan, return(cat(p)[0] does not work. On the front end, when I do this cosole.log(ouput), I get object{} — user1471980
– user1471980, Commented Aug 11, 2014 at 11:19

Rich Scriven · Accepted Answer · 2014-08-10 03:55:39Z

1

I'm fairly certain that the only way to suppress the [1] is to output the function return value with cat. The only issue with this is that even if you assign your function to a variable, say g <- f() below, it will always print.

> f <- function() {
      cat(1:10)
  }
> f()
1 2 3 4 5 6 7 8 9 10
> g <- f()   ## still prints, even though I assigned it to a variable
1 2 3 4 5 6 7 8 9 10

If the latter isn't a problem for you, then this might be the way to go.

answered Aug 10, 2014 at 3:55

Rich Scriven

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6 Comments

user1471980 Over a year ago

when I run the function locally, I dont get the [1]. But when I call this function remotely via ajax call, I get [object object], no data. I am not sure what is going on here.

Rich Scriven Over a year ago

It literally says "object object" ?

user1471980 Over a year ago

when I do document.write(output of the function), I get [object Object]

user1471980 Over a year ago

When I use print(p), I see the data on document.write, I dont get what's happening here.

Rich Scriven Over a year ago

Neither do I . It sounds like a dispatch issue. Have you tried running a little sample script (like one line of code) and see if that works remotely?

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