[Numpy-discussion] insanely slow writing to memory mapped array

Charles R Harris charlesr.harris at gmail.com
Wed Nov 29 21:24:25 CST 2006


On 11/29/06, Mathew Yeates <myeates at jpl.nasa.gov> wrote:
>
> whoa. I just found out that A=A.transpose() does nothing but change A's
> flags from C_CONTIGUOUS to F_CONTIGUOUS!!
>
> Okay, so heres the question ...... I am reading data into the columns of
> a matrix. In order to speed this up, I want to read values into the rows
> of a matrix and when I am all done, do a transpose. Whats the best way?


And if you just want to read in the data from the file in one big contiquous
binary chunk:

>>> a = fromfile("foo.data", dtype=whatever).reshape(m,n)

Then you can make a transposed copy of a. Or even a transposed view,
depending on how you want to use it.

Chuck
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