[Numpy-discussion] fromstring, tostring slow?

Mark Janikas mjanikas@esri....
Tue Feb 13 13:42:35 CST 2007

Hello all,


I am finding that directly packing numpy arrays into binary using the
tostring and fromstring methods do not provide a speed improvement over
writing the same arrays to ascii files.  Obviously, the size of the
resulting files is far smaller, but I was hoping to get an improvement
in the speed of writing.  I got that speed improvement using the struct
module directly, or by using generic python arrays.  Let me further
describe my methodological issue as it may directly relate to any
solution you might have.


My output file is heterogeneous.  Each line is either an array of
integers or floats.  Each record is made up of three entries.

They serve as a sparse representation of a large matrix.


1)       row, n (both integers)

2)       array of integers of length n, representing columns

3)       array of floats of length n, representing values



Here, "n" is not constant across the records, so many of the database
structures I have looked at do not apply.  Any suggestions would be
greatly appreciated.



Mark Janikas

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