我很好奇shape的 (9,) ,是指9行1列还是1行9列?最后的numarr2好象是1行9列,但是(9,)却好象是要求9行1列?请指教.谢谢!
>>> from numpy import *
>>> numarr2
array([[ 2,  4,  6],
       [ 8, 10, 12],
       [14, 16, 18]])
>>> numarr2.shape = (9,)
>>> print numarr2
[ 2  4  6  8  0 12 14 16 18]

On 4/27/07, linda. s <samrobertsmith at gmail.com> wrote:
> 我很好奇shape的 (9,) ,是指9行1列还是1行9列?最后的numarr2好象是1行9列,但是(9,)却好象是要求9行1列?请指教.谢谢!
> >>> from numpy import *
> >>> numarr2
> array([[ 2,  4,  6],
>        [ 8, 10, 12],
>        [14, 16, 18]])
> >>> numarr2.shape = (9,)
> >>> print numarr2
> [ 2  4  6  8  0 12 14 16 18]



9行一列 好像应该这样写
numarr2.shape = (9,1)

一行九列 是 numarr2.shape = (1,9)

On Fri, Apr 27, 2007 at 09:32:10AM +0800, lubiao wrote:
> On 4/27/07, linda. s <samrobertsmith在gmail.com> wrote:
> > 我很好奇shape的 (9,) ,是指9行1列还是1行9列?最后的numarr2好象是1行9列,但是(9,)却好象是要求9行1列?请指教.谢谢!
> > >>> from numpy import *
> > >>> numarr2
> > array([[ 2,  4,  6],
> >        [ 8, 10, 12],
> >        [14, 16, 18]])
> > >>> numarr2.shape = (9,)
> > >>> print numarr2
> > [ 2  4  6  8  0 12 14 16 18]
> 
> 
> 
> 9行一列 好像应该这样写
> numarr2.shape = (9,1)
> 
> 一行九列 是 numarr2.shape = (1,9)
这个我也觉得很奇怪，按照文档里面写的应该把(9,)理解成9行。但是文档里面的例子也是这种写法，所以我个人把他当做特例单独记住。

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ÔÚ07-4-27£¬Ken Lai <soulhacker511在163.com> дµÀ£º
>
> On Fri, Apr 27, 2007 at 09:32:10AM +0800, lubiao wrote:
> > On 4/27/07, linda. s <samrobertsmith在gmail.com> wrote:
> > > ÎҺܺÃÆæshapeµÄ (9,) ,ÊÇÖ¸9ÐÐ1Áл¹ÊÇ1ÐÐ9ÁÐ?×îºóµÄnumarr2ºÃÏóÊÇ1ÐÐ9ÁÐ,µ«ÊÇ(9,)È´ºÃÏóÊÇÒªÇó9ÐÐ1ÁÐ?Çë
> Ö¸½Ì.лл!
> > > >>> from numpy import *
> > > >>> numarr2
> > > array([[ 2,  4,  6],
> > >        [ 8, 10, 12],
> > >        [14, 16, 18]])
> > > >>> numarr2.shape = (9,)
> > > >>> print numarr2
> > > [ 2  4  6  8  0 12 14 16 18]
> >
> >
> >
> > 9ÐÐÒ»ÁÐ ºÃÏñÓ¦¸ÃÕâÑùд
> > numarr2.shape = (9,1)
> >
> > Ò»ÐоÅÁÐ ÊÇ numarr2.shape = (1,9)
> Õâ¸öÎÒÒ²¾õµÃºÜÆæ¹Ö£¬°´ÕÕÎĵµÀïÃæдµÄÓ¦¸Ã°Ñ(9,)Àí½â³É9ÐС£µ«ÊÇÎĵµÀïÃæµÄÀý×ÓÒ²ÊÇÕâÖÖд·¨£¬ËùÒÔÎÒ¸öÈË°ÑËûµ±×öÌØÀýµ¥¶À¼Çס¡£
>
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On Fri, Apr 27, 2007 at 07:11:57PM +0800, Li Qingfeng wrote:
> 不知道是不是我对numpy的使用有问题，用numpy写的神经网络程序速度比C++还是相去甚
> 远，甚至比纯python程序也快不了多少。
python程序运行的速度应该比cpp慢：python是解释性的嘛。至于使用与不使用的速度，我觉得当数据量大了可能会有些优势，不过我没有实际遇到数据量大的情况。：（用numpy是因为对数组操作方便，真是很爽。