I'm looking for a library capable of drawing dendrograms of data in Java (not calculating them, I can do it by myself).. do you have any clues? Already tried to search it over Google but haven't found anything that is not stand-alone (while I need to embed the generation inside my program).
Thanks!
Check out the JUNG graph library. It won't perform the actual clustering for you but is a really good library for visualising your results.
Take a look at Archaeopteryx. It has fairly many features; it's open source, and it is available in a pre-packaged jar file.
BTW, I use JUNG and really like it. It can perform various clusterings, but AFAIK, it has no inherent dendrogram capabilities. Because it has graphing capabilities, you could roll your own dendrogram, but it would take some work.
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I am creating an application were I have to do a lot of mathematical calculations and finally print a report with the results(which consists of a lot of statistics/graphs etc.)
I thought about using R in my application. However I did not found a stable library?
Instead I want to use: apache maths and probably some plotting library(graphs).
Therefore,
Do you have any recommendations either on a RToJava and also on a java plotting library?
PS.: One thing I forgot: I am on time pressure on this project and therefore I need something that is stable!
I'm doing some statistical analysis now, using apache-commons-math3 and JFreeChart. JFreeChart itself is free but the developer manual is commercial. But there are plenty of examples and posts to be found on SO and the rest of the web, so if you don't want to buy the manual you can still find all you need to know but it requires a bit of searching.
JFreeChart is probably the most popular charting/plotting library for Java.
I have a set of categorized text files. I want to categorize another large set of text files to use in my research. Is there a good way to compare them?
I think SVM based methods are useful but is there a simple and documented library for using such algorithms?
I don't know much about SVM, but LingPipe might be really helpful for you. The link is a tutorial specifically about categorization of documents (automatic or guided).
Also, look into the inter-related search products Lucene (a search library), Solr (search server app), and Carrot2 (for 'clustering' search results). There should be some interesting work in that space for you.
Mallet is another awesome library to look into. It has good commandline tools to help you get started and a Java API once you start getting into integrating it with the rest of your system.
I need a java graph library for visualization that I can incorporate in my own application. I found that jgraph is excellent for visualization but require explicit positioning of the nodes. Is there any open source java graph library that support automatic layout. Any suggestion will be really helpful for me.
There are numerous packages to do that.
If you are used to graphviz, then you may like Grappa, which is a sort of graphviz library for java (though not as complete as the original).
jung is also quite good, providing various layout engines.
Another tool of interest to build nice graph visualizations and animations is prefuse. It it very flexible, and can lead to very good looking visualizations, with complex layouts.
All of them are java libraries, and open source.
I've used JGo for years with success - not free (has free eval).
http://www.nwoods.com/go/jgo.htm
It has autolayout options for digraphs and force-directed, for sure, maybe more. I think the newer versions are much spiffier.
JGraph does support automatic layout and includes a number of graph and hieracichal layout algorithms.
See the API reference and example code for details.
Is it possible that anyone has a link to a graph class/library that I can use to produce a graph in Java?
Thanks for any help!
My top choice would be JGraph as others have suggested; I am using JGraph5 because it is better documented than the newer alternative, JGraphX. EDIT: JGraphX turns out to be the far superior version, despite the lack of documentation. It's not that hard to figure out.
JGraph
Demonstration app
Feature list
Licensing agreement
Other alternatives I've researched:
JGraphT
"JGraphT is a free Java graph library that provides mathematical graph-theory objects and algorithms...complete source code included, under the terms of the GNU Lesser General Public License." (http://jgrapht.sourceforge.net/)
Main project repository
Example visualizations
JUNG - Java Universal Network/Graph Framework
Main project repository
yEd Graph Editor
Implementation of yFiles library
Demonstration Java applet
About yEd
Saves graphs in GraphML format
I used JGraph as a visualizer for networks of nodes/topologies at my previous job, it's not half bad once you get past the architecture (it's a big state machine if I recall correctly).
Visual graph: JFreeChart
You may also wish to consider the Google Charts API, if you can make web service requests.
A really good alternative is to used the Google Charts API. Platform independent, easy to use, and fast processing (done on Google Server side)
graphviz would be my choice. It's not Java, but still terrific and easy to use.
There is a Java component that works with dot to generate graphs. I've used it - very nice, indeed.
I would recommend JGraphT. I used it to create multi-leveled graphs in my dissertation and as the base of a GPS Routing Software, understanding what is going on I found a bit of a mind bender, but once looking at how the algorithms package works I found it quite easy to implement A*/D* heuristic algorithms. For working out the distance between nodes on the graph I'd also recommend looking at the Haversine function, if that's your thing.
I want to open and manipulate Excel files with ActiveX. I've had success with Python's Win32 Extensions and Groovy's Scriptom libraries on other projects but need to do this is pure Java this time if possible.
I've tried the Jacob Java COM Bridge but that doesn't seem as straightforward or simple to use, and I couldn't get it to retrieve cell values (even though this is the library underlying Scriptom). Are there alternatives?
Jacob is really the tool for the job here. I recommend that you take the time to learn a bit about how COM and ActiveX work, and I think you'll find that it's easier to use. COM is quite an accomplishment, but it's hard. Wrappers like VB make it seem easy (For the limited use that they work for), but it is not at all easy. I have a great book on learning COM, but don't have the name handy right now...
You want to learn about the IDispatch interface (this is what most of Excel's COM interface is developed around). It's a nasty, nasty interface (one of those viral things that you can do so much with it that it becomes impossible to tell what is actually happening) - but learning it is key.
If you are having issues in just one area (i.e. getting a value from a cell), you could grab the source for Scriptom and see what they do (open source, after all!).
Another suggestion is to try to implement some test cases of your code in VBA and make sure that you are correctly thinking through all the return values. When we were doing Excel automation in one of our Java apps, we implemented the general algorithm from Word's VBA, worked through the problem cases, etc... After that, transferring over to Jacob was pretty straightforward.
K
how about http://www.nevaobject.com/_docs/_java2com/java2com.htm -- this is commercial but works better.
Have you looked at JExcelAPI? Instead of using ActiveX this is a Java library which directly reads and writes Excel files.
Not an exact answer to your questions but it might solve the problem just as well, especially if you're looking for a pure Java solution.
There's also JIntegra, which does a similar thing. Also commercial.
And there's JNIWrapper, which does a similar thing. again, also commercial.