Re: [Gretl-users] Python and Gretl
Am 26.01.2013 20:18, schrieb Allin Cottrell:
On Sat, 26 Jan 2013, Pietro Battiston wrote:
> I love Gretl's "foreign" code blocks capability, and would love even
> more the possibility of using Python in them, which was at some time
> suggested as easy to implement.
Yes, quite easy. In fact, so easy that Python support is now
in gretl CVS and the snapshots for Windows and OS X. Here's a
trivial example:
This is wonderful, thank you Allin!
<hansl>
matrix M = I(5)
mwrite(M, "(a)dotdir/pytest.mat")
foreign language=python
Not a big issue, but this treats Python as somehow equivalent to Numpy.
I wonder whether this should be made explicit, also given that the
"import numpy" line is hidden. So maybe 'language=numpy' or
'nppython'?
...
When python is invoked via gretl, one thing that happens
automatically is:
import numpy as np
This is in part because numpy is needed for the implementation
of gretl_loadmat and gretl_export, which use np.loadtxt and
np.savetxt respectively. I'm not a python person, but I
suspect that some users might not like the "import" statement
as I have it. Comments welcome.
There is certainly nothing wrong with this import statement, but it is a
"secret" in some sense, even though it will be in the docs. Maybe
introduce an argument where the abbreviation can be set, as in 'foreign
language=numpy --as="np"'?
Related question: in Python, as in R, Octave and Ox, the
"dotdir" business (which ensures we have a user-writable and
gretl-findable location) is hidden from the matrix read/write
functions, but on the gretl end you have to use @dotdir
explicitly with mwrite and mread when interfacing with
"foreign".
Any sale for a pair of gretl functions mexport() and mimport()
which handle the prepending of dotdir automatically?
Well if you're begging for feature request, you can have them :-)
One comment though: Instead of introducing new functions, maybe it would
be better to modify the existing mwrite() and mread() functions to
prepend @dotdir by default if the string is recognized as a relative
path. (Caveat: The directory lookup stuff is tricky, and I haven't
thought this through. There could be some interference with workdir.
Maybe need to introduce another optional argument in the functions.)
Again, many thanks for python support!
cheers,
sven