从Rserve调用ggplot。 1KB的空白png图像[重复]

Question

这个问题在这里已有答案：

• ggplot's qplot does not execute on sourcing 1回答

我最近一直在使用r，rserve和ggplot。

在R控制台中执行此代码时，会直接呈现带有两个条形的图表。 png（file ='Yash_GenderVsTotalAccountBalance.png'，width = 400，height = 350，res = 72）ggplot（data = YashCustomersAccounts，aes（x = GENDER_DESC，y = ACCOUNT_BALANCE））+ geom_bar（stat ='identity'）dev。关闭（）

但是当我使用Rserve从JAVA调用相同的代码（涉及ggplot调用）时，它会创建一个空白的png。代码如下。

package RRnD;
import java.awt.*;
import org.rosuda.REngine.*;
import org.rosuda.REngine.Rserve.*;

public class PlottingGenderVsTotalAccountBalance {

    public static void main(String[] args) throws RserveException {
        try {
            RConnection c = new RConnection(); // make a new local connection on default port (6311)
            System.out.println("1. Connection created ----------------------------------------------------------------------");            
            System.out.println("Working directory = "+c.eval("getwd()").asString());
            System.out.println("2. Working dir read ----------------------------------------------------------------------");
            c.eval("YashCustomers <- read.csv('YashCustomer.csv', header=TRUE)");
            c.eval("YashAccounts <- read.csv('YashAccount.csv', header=TRUE)");
            c.eval("YashCustomersAccounts <- merge(YashCustomers,YashAccounts, by='CUSTOMER_ID')");
            System.out.println("3. Data.frames read ----------------------------------------------------------------------");

            c.eval("library(ggplot2)");
            c.eval("require(ggplot2)");
            System.out.println("4. ggplot2 loaded ----------------------------------------------------------------------");

            c.eval("png(file='Yash_GenderVsTotalAccountBalance.png',width=400,height=350,res=72)");
            c.parseAndEval("ggplot(data=YashCustomersAccounts, aes(x=GENDER_DESC,y=ACCOUNT_BALANCE)) + geom_bar(stat='identity');dev.off()");            
            System.out.println("5. plotting done ----------------------------------------------------------------------");

            REXP xp = c.parseAndEval("r=readBin('Yash_GenderVsTotalAccountBalance.png','raw',1024*1024)");
            c.parseAndEval("unlink('Yash_GenderVsTotalAccountBalance.jpg'); r");
            Image img = Toolkit.getDefaultToolkit().createImage(xp.asBytes());
            System.out.println("img = "+img);
            System.out.println("6. File reading done ----------------------------------------------------------------------");

            System.out.println("10. All done ----------------------------------------------------------------------");            
            c.close();
        } catch (REngineException ree) {
            System.out.println("REngineException ...");
            System.out.println(ree.getMessage());
        } catch (Exception e) {
            System.out.println("Exception ...");
            System.out.println(e.getMessage());
        }
    }

}

注意： - 如果我像下面一行做一个简单的情节调用，它可以正常工作，而不是ggplot调用。 png图像正确创建。 c.parseAndEval（ “图（YashCustomers [ 'CUSTOMER_ID']）; dev.off（）”）; ...而不是... c.parseAndEval（“ggplot（data = YashCustomersAccounts，aes（x = GENDER_DESC，y = ACCOUNT_BALANCE））+ geom_bar（stat ='identity'）; dev.off（）”）;

请帮助我找到问题。非常感谢， - Yash

Answer 1

在控制台ggplot中自动绘制图像。但是在从Rserver调用ggplot绘图时，我们需要明确地打印图像。

c.parseAndEval("print(ggplot(data=YashCustomersAccounts, aes(x=GENDER_DESC,y=ACCOUNT_BALANCE)) + geom_bar(stat='identity'));dev.off()");