Using NumPy and Cpython with Jython

Question

I must use a commercial Java library, and would like to do it from Python. Jython is robust and I am fine with it being a few dot releases behind. However, I would like to use NumPy as well, which obviously does not work with Jython. Options like CPype and Java numeric libraries are unappealing. The former is essentially dead. The latter are mostly immature and lack the ease of use and wide acceptance of NumPy. My question is: How can one have Jython and Python code interoperate? It would be acceptable for me to call Jython from Cpython or the other way around.

Answer 1

It's ironic, considering that Jython and Numeric (NumPy's ancestor) were initiated by the same developer (Jim Hugunin, who then moved on to also initiate IronPython and now holds some kind of senior architect position at Microsoft, working on all kind of dynamic languages support for .NET and Silverlight), that there's no really good way to use numpy in Jython. The closest thing to that, which I know of, is the "jnumerical" project -- the (scarce) docs are on sourceforge, but the updated sources are on bitbucket.

"Numeric Python", what jnumerical implements, is not as slick and streamlined as its numpy descendant, but it has about the same functionality and shares a lot of the concepts and philosophy, so maybe you could find it usable -- worth checking out, at least.

Answer 2

Consider using execnet, which allows you to combine the strengths of both Jython and CPython, including current NumPy. The disadvantage here is that you will have to pay for the cost of serializing/deserializing objects between the two interpreters in two different process spaces. (You can avoid network overhead by using its support for subprocess.) But such a combination may work well, given that you're considering JPype, which would have similar (and probably higher) overhead. Just ensure you've partitioned the work appropriately.

The Jython developers (and I'm one of them) are looking at supporting NumPy in the future, via support of the C Extension API, but this is very much preliminary planning indeed.