Soeren Sonnenburg wrote:

Dear all,

I am new to numarray and as I am trying to use it day-by-day I am now wondering about certain numeric/numarray design issues. Please forgive me / correct me as I probably misunderstood certain issues.

-- Why did you choose row-major instead of column major format as practiced by R/octave/matlab... Doesn't that mean performance problems as fortran/blas is optimized if you work with the transposed version ?

Not everyone is interfacing with optimized FORTRAN code. Those who are are usually using ATLAS as their BLAS, and ATLAS has row-major versions of the BLAS subroutines. Row-major is C's convention and numarray/Numeric largely follow that. There are of course some performance issues when interfacing with FORTRAN code that expects column-major, but there would be other performance problems if numarray/Numeric were column-major and interfacing with row-major code.

-- why do vectors have no 'orientation', i.e. there are only row but no column vectors (or why do you treat matrices/vectors differently, i.e. have vectors at all as a separate type)

You can certainly make column vectors. In [1]: a = arange(5) In [2]: a Out[2]: NumPy array, format: long [0 1 2 3 4] In [3]: a.shape = (5,1) In [4]: a Out[4]: NumPy array, format: long [[0] [1] [2] [3] [4]] Often, though, a "row" vector can also be used in place of a "column" vector. Although sometimes not:

-- How can one obtain submatrices from full matrices:

In [6]: import numarray In [7]: a = numarray.arange(1, 10) In [8]: a.shape = (3,3) In [9]: a Out[9]: array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) In [10]: i = [0,1] In [11]: j = [[0],[2]] In [12]: a[i,j] Out[12]: array([[1, 4], [3, 6]])

-- why don't you allow iterating over the whole matrix via a single index ?

ravel()

Are there more elegant ways to do this ? Which issues are likely to be fixed in the future ?

None. They're not broken, just different from what you are used to. -- Robert Kern rkern@ucsd.edu "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter