[英]not able to execute R script from java program?
我在String變量中有一個Rscript,我想從Java程序執行它並將一些變量傳遞給它。 如果我獨立執行該R腳本,它可以正常工作。 我通過使用Python程序將所有R腳本轉換為一行,如下所示:
import json
jsonstr = json.dumps({"script": """\
#!/usr/bin/Rscript
# read the data file
library('jsonlite')
library('rpart')
args <- as.list(Sys.getenv(c(
"path",
"client_users")))
if (args[["path"]]==""){
args[["path"]] <- "."
}
# other stuff here
# other stuff here
"""})
print jsonstr
我使用打印出來的字符串並將其存儲在String變量中,然后我執行下面的代碼,它根本不起作用。 我將path
和client_users
變量傳遞給上面的R腳本。
public static void main(String[] args) throws IOException, InterruptedException {
// this is your script in a string
// String script = "#!/bin/bash\n\necho \"Hello World\"\n\n readonly PARAM1=$param1\n echo $PARAM1\n\nreadonly PARAM2=$param2\n echo $PARAM2\n\n";
String script = "above R Script here";
List<String> commandList = new ArrayList<>();
commandList.add("/bin/bash");
ProcessBuilder builder = new ProcessBuilder(commandList);
builder.environment().put("path", "/home/david");
builder.environment().put("client_users", "1000");
builder.redirectErrorStream(true);
Process shell = builder.start();
// Send your script to the input of the shell, something
// like doing cat script.sh | bash in the terminal
try(OutputStream commands = shell.getOutputStream()) {
commands.write(script.getBytes());
}
// read the outcome
try(BufferedReader reader = new BufferedReader(new InputStreamReader(shell.getInputStream()))) {
String line;
while((line = reader.readLine()) != null) {
System.out.println(line);
}
}
// check the exit code
int exitCode = shell.waitFor();
System.out.println("EXIT CODE: " + exitCode);
}
上面的代碼適用於bash shell腳本。 我需要為R腳本做些什么特別的事嗎? 我將對bash腳本和R腳本使用相同的代碼。
這是我得到的錯誤:
/bin/bash: line 7: -: No such file or directory /bin/bash: line 10: syntax error near unexpected token `'jsonlite'' /bin/bash: line 10: `library('jsonlite')'
如果我刪除commandList.add("/bin/bash");
並添加commandList.add("/bin/Rscript");
然后我看到下面的錯誤:
Cannot run program "/bin/Rscript": error=2, No such file or directory
更新: -
我沒有使用上面的腳本,而是決定在r中使用簡單的打印地獄腳本來查看是否可以通過Java執行它。
// this will print hello
String script = "#!/usr/bin/env Rscript\nsayHello <- function(){\n print('hello')\n}\n\nsayHello()\n";
當我用commandList.add("/bin/bash");
執行此腳本時commandList.add("/bin/bash");
,我收到此錯誤:
/bin/bash: line 2: syntax error near unexpected token `('
/bin/bash: line 2: `sayHello <- function(){'
但是如果我用這個commandList.add("/bin/sh");
,我收到此錯誤:
/bin/sh: 2: Syntax error: "(" unexpected
您必須直接運行/usr/bin/Rscript
。 此外,此程序不讀取標准輸入中的腳本(您必須指定腳本的路徑作為Rscript
的參數),因此您必須:
例如,這是一個POC:
public static void main(String[] args) throws IOException, InterruptedException {
// Your script
String script = "#!/usr/bin/env Rscript\n" +
"\n" +
"sayHello <- function() {\n" +
" print('hello')\n" +
"}\n" +
"\n" +
"sayHello()\n";
// create a temp file and write your script to it
File tempScript = File.createTempFile("test_r_scripts_", "");
try(OutputStream output = new FileOutputStream(tempScript)) {
output.write(script.getBytes());
}
// build the process object and start it
List<String> commandList = new ArrayList<>();
commandList.add("/usr/bin/Rscript");
commandList.add(tempScript.getAbsolutePath());
ProcessBuilder builder = new ProcessBuilder(commandList);
builder.redirectErrorStream(true);
Process shell = builder.start();
// read the output and show it
try(BufferedReader reader = new BufferedReader(
new InputStreamReader(shell.getInputStream()))) {
String line;
while((line = reader.readLine()) != null) {
System.out.println(line);
}
}
// wait for the process to finish
int exitCode = shell.waitFor();
// delete your temp file
tempScript.delete();
// check the exit code (exit code = 0 usually means "executed ok")
System.out.println("EXIT CODE: " + exitCode);
}
作為替代方案, 如果您的腳本有第一行“shebang” ,您可以執行以下更改:
commandList.add("/usr/bin/Rscript");
) 要修改的代碼部分是:
...
// create a temp file and write your script to it
File tempScript = File.createTempFile("test_r_scripts_", "");
tempScript.setExecutable(true);
try(OutputStream output = new FileOutputStream(tempScript)) {
output.write(script.getBytes());
}
// build the process object and start it
List<String> commandList = new ArrayList<>();
commandList.add(tempScript.getAbsolutePath());
ProcessBuilder builder = new ProcessBuilder(commandList);
...
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