Java RConnection.parseAndEval方法代码示例

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * Executes an R function (return: String)
 * 
 * @param function
 *        name of the R function
 * @param parameters
 *        array of parameters required by the function
 * 
 *        TODO: make more generic - not just for Strings ...
 */
public static String executeStringFunction(RConnection conn, String function, String[] parameters) {

    try {
        // create request
        String request = "try(" + function + "(";
        for (String parameter : parameters) {
            request += parameter + ",";
        }
        // remove last ","
        request = request.substring(0, request.length() - 1);
        request += "))";
        // execute function
        REXP xp = conn.parseAndEval(request);
        if (xp.inherits("try-error")) {
            close(conn);
            throw new IOException("failed to execute function '" + function + "'; \nrequest: " + request
                    + "; \nError: " + xp.asString());
        }
        String retval = xp.asString();
        return retval;
    }
    catch (Exception e) {
        return null;
    }
}
 

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * Get an R connection
 * 
 * @param host
 * @param workspace
 * @return {@link RConnection} rConnection - a connection to RServer
 */
private static RConnection getRServeConnection(String host, String workspace) {

    try {
        // establish R connection
        RConnection conn = new RConnection(host);
        // check connection
        if (conn == null || !conn.isConnected())
            throw new IOException("Failed to establish RServe connection");

        // set workspace
        if (workspace != null) {
            REXP xp = conn.parseAndEval("try(setwd('" + workspace.replace("\\", "\\\\") + "'))");
            if (xp.inherits("try-error"))
                throw new IOException("Failed to load R workspace; \nError: " + xp.asString());
        }
        return conn;
    }
    catch (Exception e) {
        return null;
    }
}
 

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * <p>
 * The RContainer constructor opens a connection (an RConnection) to either
 * local or remote RServe, and combines the object with the current Vaadin
 * main window. Thus, the main window must have been set earlier with
 * {@link com.vaadin.Application#setMainWindow(Window)} for the grahics to
 * work. See {@link RContainer#RContainer(Application, String, int)} for
 * accessing remote R Servers.
 * </p>
 * 
 * <p>
 * Example:<br>
 * {@code Window main = new Window("My Fabulous Analysis App");}<br>
 * {@code setMainWindow(main);}<br>
 * {@code RContainer R = new RContainer(main.getApplication());}
 * </p>
 * 
 * @param app
 *            Vaadin Application reference. Needed in the construction of
 *            StreamResource objects for R graphics.
 */
public RContainer() {

	try {
		rc = new RConnection();
		rc.parseAndEval("library('Cairo')");

	} catch (Exception e) {
		if (verboseErrors) {
			Notification.show("RVaadin: Could not connect to R.",
					Notification.Type.ERROR_MESSAGE);
		}
		e.printStackTrace();
	}

	/*
	 * Random session identifier for this particular R connection (used to
	 * e.g. tell the browser not to cache the images)
	 */
	rand = new Random((new GregorianCalendar()).getTimeInMillis());
	String chars = "abcdefghijklmnopqrstuvwxyz";
	sessionID = getRandomString(rand, chars, 10);

}
 

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * Executes an R function (return: void)
 * 
 * @param function
 *        name of the R function
 * @param Parameters
 *        array of parameters required by the function
 */
public static boolean executeVoidFunction(RConnection conn, String function, String[] parameters) {
    // create request
    try {
        String request = "try(" + function + "(";
        if (parameters.length != 0) {
            for (String parameter : parameters) {
                request += parameter + ",";
            }
            // remove last ","
            request = request.substring(0, request.length() - 1);
            request += "))";
        }
        // execute function
        REXP xp = conn.parseAndEval(request);
        if (xp.inherits("try-error")) {
            close(conn);
            throw new IOException("failed to execute function '" + function + "'; \nrequest: " + request
                    + "; \nError: " + xp.asString());
        }
        return true;
    }
    catch (Exception e) {
        return false;
    }

}
 

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * Load RData workspace
 * 
 * @param RData
 *        Name of the RData file, relative to R workspace
 */
private static boolean loadRDataWorkspace(RConnection conn, String rData) {
    // load specified RData file from workspace
    try {
        REXP xp = conn.parseAndEval("try(load(paste(getwd(),'" + rData + "',sep='/')))");
        if (xp.inherits("try-error")) {
            throw new IOException("failed to load RData workspace; \nError: " + xp.toString());
        }
        return true;
    }
    catch (Exception e) {
        return false;
    }

}
 

import org.rosuda.REngine.Rserve.RConnection; //导入方法依赖的package包/类
/**
 * Close R connection
 */
private static void close(RConnection conn) {
    try {
        REXP xp = conn.parseAndEval("gc()");
        if (xp.inherits("try-error")) {
            throw new IOException("failed to load R workspace; \nError: " + xp.asString());
        }
        conn.close();
    }
    catch (Exception e) {
        // do nothing
        // should not occur
        // TODO: ...
    }
}