On Tue, Jan 24, 2012 at 7:21 PM, eat <e.antero.tammi@gmail.com> wrote:
Hi
On Wed, Jan 25, 2012 at 1:21 AM, Kathleen M Tacina < Kathleen.M.Tacina@nasa.gov> wrote:
** I found something similar, with a very simple example.
On 64-bit linux, python 2.7.2, numpy development version:
In [22]: a = 4000*np.ones((1024,1024),dtype=np.float32)
In [23]: a.mean() Out[23]: 4034.16357421875
In [24]: np.version.full_version Out[24]: '2.0.0.dev-55472ca'
But, a Windows XP machine running python 2.7.2 with numpy 1.6.1 gives:
a = np.ones((1024,1024),dtype=np.float32) a.mean() 4000.0 np.version.full_version '1.6.1'
This indeed looks very nasty, regardless of whether it is a version or platform related problem.
Looks like platform specific, same result as -eat Windows 7, Python 2.6.5 (r265:79096, Mar 19 2010, 21:48:26) [MSC v.1500 32 bit (Intel)] on win32
a = np.ones((1024,1024),dtype=np.float32) a.mean() 1.0
(4000*a).dtype dtype('float32') (4000*a).mean() 4000.0
b = np.load("data.npy") b.mean() 3045.7471999999998 b.shape (1000, 1000) b.mean(0).mean(0) 3045.7472499999999 _.dtype dtype('float64') b.dtype dtype('float32')
b.mean(dtype=np.float32) 3045.7471999999998
Josef
-eat
On Tue, 2012-01-24 at 17:12 -0600, eat wrote:
Hi,
Oddly, but numpy 1.6 seems to behave more consistent manner:
In []: sys.version
Out[]: '2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)]'
In []: np.version.version
Out[]: '1.6.0'
In []: d= np.load('data.npy')
In []: d.dtype
Out[]: dtype('float32')
In []: d.mean()
Out[]: 3045.7471999999998
In []: d.mean(dtype= np.float32)
Out[]: 3045.7471999999998
In []: d.mean(dtype= np.float64)
Out[]: 3045.747251076416
In []: (d- d.min()).mean()+ d.min()
Out[]: 3045.7472508750002
In []: d.mean(axis= 0).mean()
Out[]: 3045.7472499999999
In []: d.mean(axis= 1).mean()
Out[]: 3045.7472499999999
Or does the results of calculations depend more on the platform?
My 2 cents,
eat
-- -------------------------------------------------- Kathleen M. Tacina NASA Glenn Research Center MS 5-10 21000 Brookpark Road Cleveland, OH 44135 Telephone: (216) 433-6660 Fax: (216) 433-5802 --------------------------------------------------
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