I am trying to use Vowpal Wabbit through Java. I have downloaded and successfully compiled the code from GitHub. The command line tool works fine.
After having a quick look at the repository (especially here), I can only assume that using it through Java is supposed to be already possible, and I don't really want to reinvent the wheel.
A wrapper around Vowpal Wabbit that allows use through Java. This wrapper is designed to be self contained. Because
of the use of JNI, a number of platforms are supported in this JAR.
I have added the maven dependency (found here) to my project, but without any kind of document, I don't really know where to start.
I have seen in another question that it seems to be possible to use VW with Java, but the guy only uses Runtime.getRuntime.exec() to call his bash command, and I can't find any documentation about any other way of doing (and there are only 2 questions mixing VW and Java on SO, which doesn't help).
I am new to JNI, so most likely there is something easy that I don't see.
To be perfectly clear, my questions are :
Should I just make a valid vw command and use it through Runtime.getRuntime.exec()? This doesn't seem to be the spirit of JNI, for there is no need for any wrapper/library for this. Plus, this doesn't make it very portable.
Where (the hell) is the (Java API) documentation ?
Any kind of help or guidance would be welcome.
I was one of the two primary authors of the VW JNI wrapper. Since the posting of this question the interface has significantly changed. We now encourage users to compile the native side on their own and provide it on the java.library.path. We have updated the README significantly to show how to use the library from Java.
I totally agree with your criticism that we have not published the Java API. I will work on that the next time I modify this code. In the meantime please feel free to clone the library and run mvn install and you can generate the Java API docs yourself. They should be quite detailed as we spent a lot of effort writing detailed docs.
You may checkout vowpal wabbit JNI wrapper we've built in Indeed: https://github.com/indeedeng/vowpal-wabbit-java.
We wrote integration test that can work as usage examples and we wrote API documentation as well. Check "using the library" section of README.
Hope this will help.
I don't think this adds a lot, but none of the previous answers really provided a clear answer. Like #Macchiatow mentioned, to use the Java wrapper which comes with Vowpal Wabbit, you would:
(on the project root dir) make all java or make java
cd into java and verify the installation with mvn test
you'd then mvn install to have the Java API jarred up and placed in your local maven repository. Supposedly this builds the JNI parts on your machine, so as to fit the C/C++ libraries of your platform if you have the necessary native C/C++ libraries installed and available to the make command.
you'd supposedly be able to include the vowpal package/s from those jars in the build tool used in your own project (ant/maven/boot/leiningen/sbt/etc. as in here).
For more background maybe see the Vowpal Wabbit Java readme. I think what it tries to say there, is that if you want a ready made jar from maven central, you should make sure it's the same vowpal version you're using, but without knowing more I'd guess if you built it like above, you are by definition using the same version.
I've had the above process work off a fresh clone, with Ubuntu 16.04 and Java 8.
This link may be of some help with regards to setting up a JNI wrapper.
I wasn't able to find Java API documentation anywhere, but Java code seems well documented - did you maybe try generating Javadoc yourself from the code?
There is indeed Java JNI wrapper to have a basic access to VW. By basic I mean to teach your model and to predict probability later on. They also provide Python library that can do far more than wrapper for Java. Recently I was forced to expose few more VW methods to Java by extending code provided.
Back to the questions:
Rather use the vw-jni artifact available in central maven repo and clone their code and run make all java. I some cases compiling code yourself will be the only solution, as for example provided artifact won't run on OpenSuse (my case)
Code available pretty straight forward. VWLearners::create is a factory to get an instance of VW from Java.
Related
The documentation for ROS is terrible.
One great irony is that the Groovy and ROSJava versions of ROS was created to allow developers on platforms like Windows to utilize the great robotics SDK, while all the installation instructions are still geared toward linux/ubuntu users.
The ROSJava core documentation says:
TODO: write a guide for a strictly java installation.
I've tried to follow the instructions here on the Google Code project, but seeing as all the instructions assume I'm running Ubuntu, it is very difficult as a traditional Windows/Web developer to translate into windows instructions on my own.
The link is also broken to the GIT repo, it is moved to github: https://github.com/rosjava/rosjava_core.git
If you were looking for rosws documentation, its here. Another broken link: http://www.ros.org/doc/independent/api/rosinstall/html/
Now, wanting a versatile IDE for coding, I chose Eclipse because it can handle Python, Java and c++. Now I have no idea how to build this project with Gradle and Maven-- Heck, I'm not even sure I should be building it.
Is there a definitive installation/build tutorial for ROSJava on Windows? If not, I think it would greatly benefit the community if somebody could create a walk-through that can help developers make their first "Hello World" in robotics. I've done some processing and some light Java before, but nothing too serious. The manual should assume you are new to Java, ROS and all the dependencies/build helpers/compilers. I feel like all the instructions from Google Code and ROSWiki assume you're familiar with many tools and dependencies or are aware of the historical context of ROSJava versus Groovy versus Linux implementations. Many of the necessary tools are off the beaten path for a C#.NET, Objective C or Javascript/Web developer.
Also, a big detriment is that the pre-compiled version of the ROS SDK is outright missing from ROSWiki. "Page Does Not Exist" so, us newcomers have to also install 10-16 dependencies for compiling the core (not to mention figuring out how to configure and use them).
Additionally, build scripts named in the Wiki don't even exist yet.
Currently, I've not even gotten far enough to start encountering problems like this: Gradle Eclipse Plugin
While the ROS documentation has improved in general during the past years, the ROS Java documentation is even currently not as detailed.
Using ROS_JAVA is in fact as easy as using any other dependency if you do not use custom messages.
ROS_JAVA can be practically divided in two parts.
An API to create your own servers/clients and publishers/subscribers
A pure Java roscore
The API is perfect for accessing and consuming ROS based services/topics/actions written in any language.
The pure Java roscore can be used for testing, or installation in any system that runs Java, in cases where the C++ ROS is not supported. However it is not as complete as ROS C++.
If you do not use custom messages you can easily add the required dependencies.
The following configuration should work in gradle.
repositories {
repositories {
mavenCentral()
maven {
url "https://github.com/rosjava/rosjava_mvn_repo/raw/master"
}
}
}
dependencies {
implementation 'org.ros.rosjava_core:rosjava:[0.3,0.4)'
implementation 'org.ros.rosjava_bootstrap:message_generation:0.3.3'
implementation 'org.ros.rosjava_messages:std_msgs:0.5.11'
}
This is part of a simple "Hello World" pure Java project that I have published here.
For programming only in Java /ROS Java you do not need to install ROSjava in windows. (This is also an article I had written trying to provide some quick instructions on the issue.)
If you also need to compile messages without a ROS installation then you can also do this manually through java.
Finally it is worth noting that ROS Noetic can be installed in windows. While this is not a requirement for development using ROS java.
I want to develop a small Java program using some input like the pen of a Wacom graphictablet and found only the very active JPen project but are there some more possible alternatives without JNI or JNA (without any additional needed dll files), a pure Java implementation?
You can take a look at JTablet. From another SO thread.
It seems JPen moved to GitHub and this might be the best solution at the moment.
The other alternative solutions are not developed and maintained anymore.
https://github.com/nicarran/jpen
As I've recently started using JRuby, more specifically building Java applications using Ruby code, I've started using Java Libraries such as LWJGL and Slick.
I know JRuby changes Java method names to a more ruby-esque structure, my question is, is there any current way to generate Ruby documentation, either from source or by conversion of current documentation or even based on what JRuby exposes the methods themselves as?
At some point when JRuby 1.6.7 is out I plan on cleaning this really rough project for just such a thing:
https://github.com/enebo/noridoc
The intention is it will weave both Java and Ruby syntax together and give reasonable documentation for a Rubyist wanting to know all Ruby methods. In it's current form you should be able to generate a reasonable set of HTML docs of Java code showing you all ruby aliased methods. You will need to screw around with the javadoc comment.
Oh and we plan on making this tool available out of the box in JRuby once it is good enough to merge.
Basically, I need to run Groovy Scripts to manipulate Java objects, and GroovyShell / GroovyScriptEngine seems to be the best way to do so. Is it possible to embed Groovy inside a Java App? I tried placing the groovy-all-1.8.2.jar into my Android Java App's libs folder, referenced it then hit compile but I got a bunch of errors.
How do I do this?
I don't believe this will work. Groovy converts scripts to bytecode, and as the Dalvik bytecode is different to the Java bytecode that Groovy expects, I believe it will have problems...
The Discobot from a few years ago has been resurrected though, and great progress is being made so there is hope on the horizon.
But that doesn't help you today...
In near future it will be possible: http://skillsmatter.com/podcast/home/groovy-android/
I have found it recelty.
You can find the solution from http://melix.github.io/blog/2014/06/grooid.html.
Check it http://glaforge.appspot.com/article/groovy-2-3-3-and-groovy-2-4-beta-1-with-android-support too!
Since 09/2011, Discobot seems to be stuck. The last results seem to be : most of it works, but this is very slow.
Groovy 2.0 is out now, and Guillaume Laforge (insider) says it could helps - especially because of the #CompileStatic new feature of Groovy 2.0. Since then, Groovy 2.0.1...2.0.4, it looks that static compilation got a lot of bugfixes.
But for now, on the official website of Groovy, Android is not discussed, nobody seems to really be in charge (see wiki and wiki).
Here is an example of what you are trying to accomplish. https://github.com/melix/grooidshell-example
It is pretty slow since it has to first compile to class files on the android device and then convert them to dex, but it will accomplish what you are looking for.
A better choice for running scripts on Android is SnapScript. It does not rely on Bytecode and is fully supported on Android.
Is it possible to write Jenkins plugins using Python (via Jython), and if so, where would I get started? I don't know Java (and don't have a real interest in learning it at the moment) so being able to use Python would be nice for me.
There's no docs on that. Frankly your problem with be you must understand how the interfaces and extensions map from java to jython to write it.
Here are links on writing Jenkins plugins
Let's you embed either Jython or Python scripts and run them from a plugin If all you nee to do is run a simple script, that be what you need.
If your goal is to execute Jython code within Jenkins, you may want to have a look at the Jython Plugin.
Starting version 1.6, you can actually install Jython packages (say if you have your own library you'd like to use), and it'll automatically sync up the packages across all Jenkins slaves.
Since Jython can produce Java classes I see no reason why this should not work.
Note that you will need to learn at least some things about Java (mostly the platform, not necessarily the language) in order to be able to write plugins for Jenkins.