Re: [Numpy-discussion] Need faster equivalent to digitize

2010-04-14 Thread Peter Shinners
On 04/14/2010 11:34 PM, Nadav Horesh wrote: > import numpy as N > N.repeat(N.arange(len(a)), a) > >Nadav > > -Original Message- > From: numpy-discussion-boun...@scipy.org on behalf of Peter Shinners > Sent: Thu 15-Apr-10 08:30 > To: Discussion of Numeric

[Numpy-discussion] Need faster equivalent to digitize

2010-04-14 Thread Peter Shinners
I am using digitize to create a list of indices. This is giving me exactly what I want, but it's terribly slow. Digitize is obviously not the tool I want for this case, but what numpy alternative do I have? I have an array like np.array((4, 3, 3)). I need to create an index array with each inde

[Numpy-discussion] How to combine a pair of 1D arrays?

2010-04-14 Thread Peter Shinners
Is there a way to combine two 1D arrays with the same size into a 2D array? It seems like the internal pointers and strides could be combined. My primary goal is to not make any copies of the data. It might be doable with a bit of ctypes if there is not a native numpy call. >>> import numpy as

Re: [Numpy-discussion] how to tally the values seen

2010-04-14 Thread Peter Shinners
On 04/13/2010 11:44 PM, Gökhan Sever wrote: On Wed, Apr 14, 2010 at 1:34 AM, Warren Weckesser <mailto:warren.weckes...@enthought.com>> wrote: Gökhan Sever wrote: > > > On Wed, Apr 14, 2010 at 1:10 AM, Peter Shinners mailto:p...@shinners.or

[Numpy-discussion] how to tally the values seen

2010-04-13 Thread Peter Shinners
I have an array that represents the number of times a value has been given. I'm trying to find a direct numpy way to add into these sums without requiring a Python loop. For example, say there are 10 possible values. I start with an array of zeros. >>> counts = numpy.zeros(10, numpy.int) Now

Re: [Numpy-discussion] take not respecting masked arrays?

2010-03-01 Thread Peter Shinners
On 02/28/2010 10:58 PM, Pierre GM wrote: > On Mar 1, 2010, at 1:02 AM, Peter Shinners wrote: > >>> Here is the code as I would like it to work. >>> >> http://python.pastebin.com/CsEnUrSa >> >> >> import numpy as np >> >> v

Re: [Numpy-discussion] take not respecting masked arrays?

2010-02-28 Thread Peter Shinners
On 02/28/2010 08:01 PM, Pierre GM wrote: > On Feb 28, 2010, at 8:59 PM, Peter Shinners wrote: > >> I have a 2D masked array that has indices into a 1D array. I want to use >> some form of "take" to fetch the values into the 2D array. I've tried >> both

[Numpy-discussion] take not respecting masked arrays?

2010-02-28 Thread Peter Shinners
I have a 2D masked array that has indices into a 1D array. I want to use some form of "take" to fetch the values into the 2D array. I've tried both numpy.take and numpy.ma.take, but they both return a new unmasked array. I can get it working by converting the take results into a masked array a

Re: [Numpy-discussion] Want cumsum-like function

2010-02-25 Thread Peter Shinners
On 02/24/2010 11:48 PM, Friedrich Romstedt wrote: > 2010/2/25 Peter Shinners: > >> I want a function that works like cumsum, but starts at zero, instead of >> starting with the first actual value. >> >> [...] >> >> tallies = np.cumsum(initial_array) &

Re: [Numpy-discussion] Want cumsum-like function

2010-02-24 Thread Peter Shinners
On 02/24/2010 09:00 PM, Robert Kern wrote: > On Wed, Feb 24, 2010 at 22:53, Peter Shinners wrote: > >> I want a function that works like cumsum, but starts at zero, instead of >> starting with the first actual value. >> >> For example; I have an array with [4,3,3

[Numpy-discussion] Want cumsum-like function

2010-02-24 Thread Peter Shinners
I want a function that works like cumsum, but starts at zero, instead of starting with the first actual value. For example; I have an array with [4,3,3,1]. Cumsum will give me an array with [4,7,10,11]. I want an array that is like [0,4,7,8]. It looks like I could indirectly do this: tallies =