On 01/11/10 07:28, Denham Robert wrote:
> I got caught out converting a 3d array in R to a numpy array. I did
> something like:
>
> import numpy
> import rpy2
> import rpy2.robjects as robjects
>
> marr = robjects.r.array(robjects.IntVector(range(54)),dim=
> robjects.IntVector([9,2,3]))
> marrpy = numpy.array(marr)
> print marrpy.flatten()
> print robjects.r['as.vector'](marr)
>
> Which clearly doesn't work (at least for me, using rpy2.1.7, R-10.0 on
> 64bit suse linux).
Could you be more specific about "does not work" ?
If you are after getting the same output for the two print calls, this
is not happening because arrays are being stored "column-major" by R by
while numpy has "row-major" as a default.
Try:
print marrpy.flatten('F')
> The matrix version does work, eg
>
> mat = robjects.r.matrix(robjects.IntVector(range(54)),nrow=9)
> matpy = numpy.array(mat)
> print mat
> print matpy
>
> I checked the documentation, and found examples for vectors and
> matrices, but not for arrays, but also no warnings. So, I was just
> wondering, is this supposed to work? If it is, a hint on why it doesn't
> work for me would be good. If it isn't supposed to work, I was wondering
> if it were possible to throw an error or something.
It is supposed to work, but not claim about an absence of bugs is made.
Best,
Laurent
> Regards,
> Robert
>
>
>
> Robert Denham
> Environmental Statistician, Remote Sensing Centre
> Environment and Resource Sciences
> Phone 07 3896 9899 (ext 69899)
> Email: robert.den...@derm.qld.gov.au
> www.derm.qld.gov.au<http://www.derm.qld.gov.au/>
>
> Department of Environment and Resource Management
> QCCE Building, 80 Meiers Rd, Indooroopilly QLD 4068
>
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