Re: [Numpy-discussion] the axis parameter in the np.ma.concatenate is not working?

2011-10-14 Thread Chao YUE
Thanks Josef, you're right. Could you explain me what's the difference between In [4]: a=np.arange(10) In [5]: a.shape Out[5]: (10,) and In [6]: a=np.arange(10).reshape(10,1) In [7]: a.shape Out[7]: (10, 1) (10) means the first a is only a one-dimensional ndarray, but the (10,1) means the

Re: [Numpy-discussion] the difference of np.nan, np.NaN, np.NAN?

2011-10-14 Thread Matthew Brett
Hi, On Fri, Oct 14, 2011 at 4:33 AM, Chao YUE chaoyue...@gmail.com wrote: Dear all, is there any difference between np.nan, np.NaN and np.NAN? they really confuse me they are all Not a Number? In [75]: np.nan==np.NaN Out[75]: False In [77]: np.NaN==np.NAN Out[77]: False The nan

Re: [Numpy-discussion] the difference of np.nan, np.NaN, np.NAN?

2011-10-14 Thread Olivier Delalleau
2011/10/14 Matthew Brett matthew.br...@gmail.com Hi, On Fri, Oct 14, 2011 at 4:33 AM, Chao YUE chaoyue...@gmail.com wrote: Dear all, is there any difference between np.nan, np.NaN and np.NAN? they really confuse me they are all Not a Number? In [75]: np.nan==np.NaN Out[75]:

Re: [Numpy-discussion] the difference of np.nan, np.NaN, np.NAN?

2011-10-14 Thread David Cournapeau
On Fri, Oct 14, 2011 at 11:53 AM, Olivier Delalleau sh...@keba.be wrote: 2011/10/14 Matthew Brett matthew.br...@gmail.com Hi, On Fri, Oct 14, 2011 at 4:33 AM, Chao YUE chaoyue...@gmail.com wrote: Dear all, is there any difference between np.nan, np.NaN and np.NAN? they really confuse

[Numpy-discussion] yet another indexing question

2011-10-14 Thread Neal Becker
suppose I have: In [10]: u Out[10]: array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]]) And I have a vector v: v = np.array ((0,1,0,1,0)) I want to form an output vector which selects items from u where v is the index of the row of u to be selected. In the above example, I want: w =

Re: [Numpy-discussion] yet another indexing question

2011-10-14 Thread Warren Weckesser
On Fri, Oct 14, 2011 at 7:04 AM, Neal Becker ndbeck...@gmail.com wrote: suppose I have: In [10]: u Out[10]: array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]]) And I have a vector v: v = np.array ((0,1,0,1,0)) I want to form an output vector which selects items from u where v is the

Re: [Numpy-discussion] yet another indexing question

2011-10-14 Thread Jean-Luc Menut
What about a=arange(len(v)) w=u[v,a] ? ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion

Re: [Numpy-discussion] yet another indexing question

2011-10-14 Thread Fabrice Silva
Le vendredi 14 octobre 2011 à 08:04 -0400, Neal Becker a écrit : suppose I have: In [10]: u Out[10]: array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]]) And I have a vector v: v = np.array ((0,1,0,1,0)) I want to form an output vector which selects items from u where v is the index

[Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t] for t=1,2,...? 1. How can I best simulate an autoregressive process using NumPy? 2. With SciPy, it looks like I could do this as e[0] = y0

Re: [Numpy-discussion] yet another indexing question

2011-10-14 Thread Neal Becker
Fabrice Silva wrote: Le vendredi 14 octobre 2011 à 08:04 -0400, Neal Becker a écrit : suppose I have: In [10]: u Out[10]: array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]]) And I have a vector v: v = np.array ((0,1,0,1,0)) I want to form an output vector which selects items from u

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t] for t=1,2,...? 1. How can I best simulate an autoregressive process using

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Fabrice Silva
Le vendredi 14 octobre 2011 à 10:49 -0400, josef.p...@gmail.com a écrit : On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e, what is the best way to produces a series y such that y[t] = 0.9*y[t-1] + e[t]

[Numpy-discussion] statistics in python

2011-10-14 Thread Radim
Hi Rense (cross-posting to the numpy mailing list because these guys are awesome), On Oct 13, 10:01 pm, Rense Lange rense.la...@gmail.com wrote: I have potentially millions of tuples v1,v2,v3 ..., observation and I want to create frequency distributions conditional on the values of discrete

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 11:56 AM, Fabrice Silva si...@lma.cnrs-mrs.fr wrote: Le vendredi 14 octobre 2011 à 10:49 -0400, josef.p...@gmail.com a écrit : On Fri, Oct 14, 2011 at 10:24 AM, Alan G Isaac alan.is...@gmail.com wrote: As a simple example, if I have y0 and a white noise series e,

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 12:49 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 12:21 PM, josef.p...@gmail.com wrote: One other way to simulate the AR is to get the (truncated) MA-representation, and then convolve can be used Assuming stationarity ... maybe ? If it's integrated,

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
Assuming stationarity ... On 10/14/2011 1:22 PM, josef.p...@gmail.com wrote: maybe ? I just meant that the MA approximation is not reliable for a non-stationary AR. E.g., http://www.jstor.org/stable/2348631 Cheers, Alan ___ NumPy-Discussion mailing

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 1:26 PM, Alan G Isaac alan.is...@gmail.com wrote: Assuming stationarity ... On 10/14/2011 1:22 PM, josef.p...@gmail.com wrote: maybe ? I just meant that the MA approximation is not reliable for a non-stationary AR. E.g., http://www.jstor.org/stable/2348631 section

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Alan G Isaac
On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm. Yes. AR(1) is trivial, but how do you handle higher orders? Thanks, Alan

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm.  Yes. AR(1) is trivial, but how do

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread Skipper Seabold
On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values is a bit difficult. Hmm.  Yes. AR(1) is trivial, but how

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:39 PM, Skipper Seabold jsseab...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:29 PM, josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter doesn't require stationarity, but handling of the starting values

Re: [Numpy-discussion] simulate AR

2011-10-14 Thread josef . pktd
On Fri, Oct 14, 2011 at 2:59 PM, josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:29 PM,  josef.p...@gmail.com wrote: On Fri, Oct 14, 2011 at 2:18 PM, Alan G Isaac alan.is...@gmail.com wrote: On 10/14/2011 1:42 PM, josef.p...@gmail.com wrote: If I remember correctly, signal.lfilter