Question

我正在尝试从Java启动R进程并重定向stdin和stdout。

processBuilder = new ProcessBuilder().command("/usr/bin/R").redirectErrorStream(
            true);
try {
        Process p = processBuilder.start();
        OutputStream stdin = p.getOutputStream();
        InputStream stdout = p.getInputStream();

        BufferedReader reader = new BufferedReader (new InputStreamReader(stdout));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(stdin));
        String line;
        while ((line = reader.readLine ()) != null) {
            System.out.println ("Stdout: " + line);
        }

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

我正在使用Java 1.6。程序运行时，我收到以下错误：

标准输出：致命错误：您必须指定'--save'，' - no-save'或'--vanilla'

任何帮助将不胜感激！谢谢！

Answer 1

您不能只使用重定向的stdin运行R而没有其中一个选项：

R < foo.R 
Fatal error: you must specify '--save', '--no-save' or '--vanilla'

你想让R在完成时保存其工作数据（--save）吗？或不（ - 没有 - 保存）？您可能会发现--vanilla适合您的使用。

--vanilla
          Combine --no-save, --no-restore, --no-site-file, --no-init-file and --no-environ

我不太清楚如何将参数传递给Java ProcessBuilder的东西，但也许只是：

processBuilder = new ProcessBuilder().command("/usr/bin/R --vanilla").redirectErrorStream(
            true);

或者它可能有设置args的方法。

Answer 2

以下是在将参数作为子进程启动时将参数传递给R的方法：

public void startR() {
    List<String> commandAndParams = new ArrayList<String>();
    commandAndParams.add("/usr/bin/R");
    commandAndParams.add("--vanilla");
    processBuilder = new ProcessBuilder().command(commandAndParams).redirectErrorStream(
            true);
    try {
        Process p = processBuilder.start();
        OutputStream stdin = p.getOutputStream();
        InputStream stdout = p.getInputStream();

        BufferedReader reader = new BufferedReader (new InputStreamReader(stdout));
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(stdin));
        String line;
        while ((line = reader.readLine ()) != null) {
            System.out.println ("Stdout: " + line);
        }

    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

结果输出为：

Stdout: 
Stdout: R version 3.0.1 (2013-05-16) -- "Good Sport"
Stdout: Copyright (C) 2013 The R Foundation for Statistical Computing
Stdout: Platform: x86_64-apple-darwin10.8.0 (64-bit)
Stdout: 
Stdout: R is free software and comes with ABSOLUTELY NO WARRANTY.
Stdout: You are welcome to redistribute it under certain conditions.
Stdout: Type 'license()' or 'licence()' for distribution details.
Stdout: 
Stdout:   Natural language support but running in an English locale
Stdout: 
Stdout: R is a collaborative project with many contributors.
Stdout: Type 'contributors()' for more information and
Stdout: 'citation()' on how to cite R or R packages in publications.
Stdout: 
Stdout: Type 'demo()' for some demos, 'help()' for on-line help, or
Stdout: 'help.start()' for an HTML browser interface to help.
Stdout: Type 'q()' to quit R.
Stdout:

从java启动R进程

2 个答案: