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今天实现了JRI方式–Java调用R方法-不用预先在R客户端启动R就可以实现连接调用

JRI，全名是Java/R Interface，这是一种完全不同的方式，通过调用R的动态链接库从而利用R中的函数等。

需要在install.packages(“rJava”)安装rJava就行，在安装文件夹中，可以看到一个jri的子文件夹，里面有自带的例子可以用来测试。

关键点在配置环境变量–我的如下：

配置好之后呢，在library里找到测试Java文件，然后在eclipse里创建一个Java工程，测一下，如下：

eclipse代码测试结果如下：

如有错误，多是环境变量配置的问题；检查jdk和r,,rJava环境变量；

修改后重启eclipse再测；出错如下，第一个是环境变量，第二个是Java，r,rJava要么都是32位的，要么都是64位的，须一致；

————————————–

Cannot find JRI native library!

Please make sure that the JRI native library is in a directory listed in java.library.path.

java.lang.UnsatisfiedLinkError: D:\software\myR\R-3.1.2\library\rJava\jri\jri.dll: Can’t find dependent libraries

at java.lang.ClassLoader$NativeLibrary.load(Native Method)

at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1965)

at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1890)

at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1880)

at java.lang.Runtime.loadLibrary0(Runtime.java:849)

at java.lang.System.loadLibrary(System.java:1088)

at org.rosuda.JRI.Rengine.(Rengine.java:19)

at com.jri.testDemo.rtest.main(rtest.java:62)

————————————–

Cannot find JRI native library!

Please make sure that the JRI native library is in a directory listed in java.library.path.

java.lang.UnsatisfiedLinkError: D:\software\myR\R-3.1.2\library\rJava\jri\jri.dll: %1 不是有效的 Win32 应用程序。

at java.lang.ClassLoader$NativeLibrary.load(Native Method)

at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1965)

at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1890)

at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1880)

at java.lang.Runtime.loadLibrary0(Runtime.java:849)

at java.lang.System.loadLibrary(System.java:1088)

at org.rosuda.JRI.Rengine.(Rengine.java:19)

at com.jri.testDemo.rtest.main(rtest.java:62)

接下来附录rtest.java文件源码注释，里面提到了Java操作R的一些API

public class rtest {

public static void main(String[] args) {

// just making sure we have the right version of everything

//确定R的版本

if (!Rengine.versionCheck()) {

System.err.println("** Version mismatch - Java files don't match library version.");//

System.exit(1);

}

System.out.println("Creating Rengine (with arguments)");

// 1) we pass the arguments from the command line //命令行处理args

// 2) we won't use the main loop at first, we'll start it later

// (that's the "false" as second argument)//第二个参数是false表示不使用main循环

// 3) the callbacks are implemented by the TextConsole class above

//创建R引擎对象，看底层是通过反射方式创建的对象

Rengine re = new Rengine(args, false, new TextConsole());

//new TestConsole()成功会打印R欢迎信息

/**

* R version 3.1.2 (2014-10-31) -- "Pumpkin Helmet"

Copyright (C) 2014 The R Foundation for Statistical Computing

R is free software and comes with ABSOLUTELY NO WARRANTY.

......

Type 'q()' to quit R.

*/

System.out.println("Rengine created, waiting for R");

// the engine creates R is a new thread, so we should wait until it's ready

// 新的线程，需要等等它准备好

if (!re.waitForR()) {

System.out.println("Cannot load R");//如果等待超时，报错: 不能加载R

return;

}

/*

* High-level API - do not use RNI methods unless there is no other way

* to accomplish what you want

*/

try {

REXP x;

re.eval("data(iris)", false);

System.out.println(x = re.eval("iris"));

//鸢尾花数据集 x=iris

// generic vectors are RVector to accomodate names

//产生R向量容纳iris数据集的字段名names 5列

RVector v = x.asVector();

if (v.getNames() != null) {

System.out.println("has names:");

for (Enumeration e = v.getNames().elements(); e.hasMoreElements();) {

System.out.println(e.nextElement());

}

}

// for compatibility with Rserve we allow casting of vectors to lists

// 通过 Rserve 把向量转成list集合

RList vl = x.asList();

String[] k = vl.keys();//[Sepal.Length, Sepal.Width, Petal.Length, Petal.Width, Species]

if (k != null) {

//遍历集合,输出names

System.out.println("and once again from the list:");

int i = 0;

while (i < k.length)

System.out.println(k[i++]);

}

// get boolean array

//产生一个Boolean数组

System.out.println(x = re.eval("iris[[1]]>mean(iris[[1]])"));//[BOOLi* ]

// R knows about TRUE/FALSE/NA, so we cannot use boolean[] this way

// instead, we use int[] which is more convenient (and what R uses internally anyway)

//将R布尔数组转为int数组？R底层处理布尔用是的0，1？NA

int[] bi = x.asIntArray();

{

int i = 0;

while (i < bi.length) {

System.out.print(bi[i] == 0 ? "F " : (bi[i] == 1 ? "T " : "NA "));

i++;

}

System.out.println("");

}

// push a boolean array

boolean by[] = { true, false, false };

re.assign("bool", by);

System.out.println(x = re.eval("bool"));//[BOOLi* ]

// asBool returns the first element of the array as RBool //返回布尔数组的第一个元素作为RBool？

// (mostly useful for boolean arrays of the length 1). is should

// return true

System.out.println("isTRUE? " + x.asBool().isTRUE());

// now for a real dotted-pair list: 对于配对的数据，类似于key=value键值对形式数据

System.out.println(x = re.eval("pairlist(a=1,b='foo',c=1:5)"));

RList l = x.asList();

if (l != null) {

int i = 0;

String[] a = l.keys();//[a, b, c]所有的键

System.out.println("Keys:");

while (i < a.length)

System.out.println(a[i++]);

System.out.println("Contents:");//

i = 0;

while (i < a.length)

System.out.println(l.at(i++));//通过索引位置取值

//[REAL* (1.0)]

//[STRING "foo"]

//[INT* (1, 2, 3, 4, 5)]

}

System.out.println(re.eval("sqrt(36)"));//[REAL* (6.0)]

} catch (Exception e) {

System.out.println("EX:" + e);

e.printStackTrace();

}

// Part 2 - low-level API - for illustration purposes only!

// System.exit(0);

//第二部分--API -low level

// simple assignment like a

//参数0表示 use R_GlobalEnv 当前环境，即用户环境，是用户程序运行的环境空间。

long xp1 = re.rniPutString("hello");

re.rniAssign("a", xp1, 0);//赋值，定义变量a

// Example: how to create a named list or data.frame创建list或数据框

double da[] = { 1.2, 2.3, 4.5 };

double db[] = { 1.4, 2.6, 4.2 };

long xp3 = re.rniPutDoubleArray(da);

long xp4 = re.rniPutDoubleArray(db);

// now build a list (generic vector is how that's called in R)

//R里的向量，Java里的list

long la[] = { xp3, xp4 };

long xp5 = re.rniPutVector(la);

// now let's add names 添加names

String sa[] = { "a", "b" };

long xp2 = re.rniPutStringArray(sa);

re.rniSetAttr(xp5, "names", xp2);

// ok, we have a proper list now 带属性的list

// we could use assign and then eval "b

// let's build it by hand:

String rn[] = { "1", "2", "3" };

long xp7 = re.rniPutStringArray(rn);

re.rniSetAttr(xp5, "row.names", xp7);

long xp6 = re.rniPutString("data.frame");

re.rniSetAttr(xp5, "class", xp6);

// assign the whole thing to the "b" variable

re.rniAssign("b", xp5, 0);

{

System.out.println("Parsing");

long e = re.rniParse("data(iris)", 1);

System.out.println("Result = " + e + ", running eval");

long r = re.rniEval(e, 0);

System.out.println("Result = " + r + ", building REXP");//REXP result = [STRING "iris"]

REXP x = new REXP(re, r);

System.out.println("REXP result = " + x);

}

{

System.out.println("Parsing");

long e = re.rniParse("iris", 1);

System.out.println("Result = " + e + ", running eval");

long r = re.rniEval(e, 0);

System.out.println("Result = " + r + ", building REXP");

REXP x = new REXP(re, r);

System.out.println("REXP result = " + x);//REXP result = [VECTOR ([REAL* (5.1, 4.9, 4.7, 4.6...

double[] doubleArray = x.asDoubleArray();

}

{

System.out.println("Parsing");

long e = re.rniParse("names(iris)", 1);

System.out.println("Result = " + e + ", running eval");

long r = re.rniEval(e, 0);

System.out.println("Result = " + r + ", building REXP");

REXP x = new REXP(re, r);

System.out.println("REXP result = " + x);//[STRING* ("Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width", "Species")]

String s[] = x.asStringArray();//[Sepal.Length, Sepal.Width, Petal.Length, Petal.Width, Species]

if (s != null) {

int i = 0;

while (i < s.length) {

System.out.println("[" + i + "] \"" + s[i] + "\"");

i++;

}

}

}

{

System.out.println("Parsing");

long e = re.rniParse("rnorm(10)", 1);

System.out.println("Result = " + e + ", running eval");

long r = re.rniEval(e, 0);

System.out.println("Result = " + r + ", building REXP");

REXP x = new REXP(re, r);

System.out.println("REXP result = " + x);

double d[] = x.asDoubleArray();

if (d != null) {

int i = 0;

while (i < d.length) {

System.out.print(((i == 0) ? "" : ", ") + d[i]);

i++;

}

System.out.println("");

}

System.out.println("");

}

{

REXP x = re.eval("1:10");

System.out.println("REXP result = " + x);

int d[] = x.asIntArray();

if (d != null) {

int i = 0;

while (i < d.length) {

System.out.print(((i == 0) ? "" : ", ") + d[i]);

i++;

}

System.out.println("");

}

}

re.eval("print(1:10/3)");

if (true) {

// so far we used R as a computational slave without REPL

// now we start the loop, so the user can use the console

System.out.println("Now the console is yours ... have fun");

re.startMainLoop();

} else {

re.end();

System.out.println("end");

}

}

具体JRI连接参考链接如下：

http://blog..net/hongweigg/article/details/45223297