The Kitchen Sink May 20, 2009
Posted by gordonwatts in ROOT.3 comments
While the plane was bouncing all over the map, it occurred to me that ROOT is a lot like Microsoft Office (indeed, any product like Office).
Looking at the list of libraries/packages in ROOT you might be tempted to call it bloatware. You’d be right, of course, but, just like MS Word and other similar programs, the libraries you think are important are different from the ones that someone else thinks are important. And almost all the libraries are available for separate use as well! But you’ll notice that few people are using it that way.
The reason is obvious – simplicity.
The brilliance of large software packages like MS Office and ROOT is not that they innovate (though both certianly do), it is that they have taken tried and true ways of doing things and made them work together by packaging them up and building bridges between them. Take TMVA, for example, the package that allows you to easily implement various multivariate analysis techniques (like a boosted decision tree). You can get that software separately – there are lots of packages out there. But TMVA is specifically designed to work with a TTree and other things in ROOT.
Once you get yourself into ROOT you have access to all these tools – and the potential barrier you have to get over to use them is minimal. You want to switch to something else? Of course you can do it – but it will be a lot of work! Just like MS Office. 
I think people complain about ROOT and how hard it is to use, but use it anyway for the same reasons they complain about MS Office and its daughter programs. Fortunately, for MS Office, there is real $$ involved so other companies are finally starting to compete – which I hope will make MS Office better. I don’t see anything like that coming along to challenge ROOT until after I retire (or there is a complete revolution in how we do data analysis in HEP).
ROOT Builder v1.31 February 26, 2009
Posted by gordonwatts in ROOT, ROOT Builder.2 comments
There are only three weeks left to term! I can’t wait! And now for something a little bit different…
This weekend I took a few hours off and finished up some remaining work on a tool Axel and I created a year ago, ROOT Builder. This is a very small windows utility that is useful if you want to build ROOT from source on your computer.
When you hit the “Generate Project” button it will create a VS 2008, 2005, or 2003 project that you can then edit and access in the IDE. Unfortunately, this is still using the ROOT make file and not a native VS IDE project (which means the build is a bit slow). However, if you decide to build debug mode then this will allow you to hit “debug” and step into ROOT right away. Very handy for those odd I/O bugs that you can’t solve with Philippe’s help!
Let me know if you have any questions.
Building ROOT on Windows March 2, 2008
Posted by gordonwatts in ROOT, computers.2 comments
Not so much interest to most people here…
So, on Windows, there has been the occasion that I’ve needed to build ROOT. In particular, on windows, this is because the released version of ROOT is not built against python. I also find myself doing lots of building building when buts are found in root (yeah, I know, ROOT doesn’t have bugs).
The standard way to do the build is download and install cygwin. It is a rather heavy install, however, as any of you who have installed it know. Axel, a member of the ROOT team, put together a minimal set of tools that will build ROOT using the MSVC compilers. I built a small UI on top of that along with an installer to make it easier to get onto your machine.
I found this pretty useful for getting my work done, so I thought I’d release it. Actually, it has been finished for months, I just never seemed to get around to finishing off the last bit. So, here it is. The UI is horrible, but it works…
Good Support January 19, 2008
Posted by gordonwatts in ROOT.2 comments
I complain about ROOT a lot. However, one thing I have to say is that when you report a bug it is only a matter of days before it gets fixed in their source code repository. Philippe Canal just did a whole bunch of work after I found a few bugs in the MakeProxy code that means it will now be possible to use weird variables like vector<vector<double> > without having to think (these are produced by the EventView tool in ATLAS). Nice!
BTW, MakeProxy is a step back in time. Remember PAW (ok, I know, some of you are still using it). One of the nice things about the FORTRAN macros back then was the auto-loading of ntuple columns. Only what you referenced in your FORTRAN code was loaded. That isn’t the case in ROOT — it has no good way to scan compiled C++ code to determine what is used. Philippe wrote an automatic proxy-generator that replaces each ntuple branch with a bit of code that first makes sure the data is read in before accessing it (I’m pretty sure Philippe was the progenitor of the idea). In the end this has the effect of doing the same thing — only what is needed is read. I’ve seen x10 speed-ups caused by this. The only it can’t do is look inside a custom compiled object — so this doesn’t buy you as much if you are running in that case.
Otherwise, I definitely recommend checking out TTree::MakeProxy.
