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Re: How can I make this piece of code even faster?

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How about using numpy?

Am 20.07.13 22:22, schrieb pablobarhamalzas@gmail.com:
> Ok, I'm working on a predator/prey simulation, which evolve using genetic algorithms. At the moment, they use a quite simple feed-forward neural network, which can change size over time. Each brain "tick" is performed by the following function (inside the Brain class):
>

>          count = -1
>          for x in range(hidden_num):
>              temp = 0
>              for y in range(input_num):
>                  count += 1
>                  temp += inputs[y] * h_weight[count]
>              hidden[x] = 1/(1+e**(-temp))

I don't really understand this loop, but it looks to me like a 
matrix-vector multiplication of the matrix of weights (indexed with a 
single continous index) with the inputs.

Given that you reshape the weights() array correctly into a 
hidden_num-by-input_num array, this would result in

import numpy as np
hidden = 1.0/(1.0 + np.exp(-np.dot(h_weights, inputs)))

The matrix-vector product is then executed by a compiled loop. You can 
reshape your existing lists into that form by

inputs = np.array(inputs)
h_weight = np.reshape(h_weight, (hidden_num, input_num))

... but of course you should use this only to check whether you get the 
correct result. You don't want to do that in the loop, instead, store 
the weights always in matrix form.

	Christian

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How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 13:22 -0700
  Re: How can I make this piece of code even faster? Fabio Zadrozny <fabiofz@gmail.com> - 2013-07-20 18:05 -0300
  Re: How can I make this piece of code even faster? Roy Smith <roy@panix.com> - 2013-07-20 17:25 -0400
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 15:45 -0700
  Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 08:55 +1000
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-20 16:24 -0700
    Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 09:29 +1000
  Re: How can I make this piece of code even faster? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-21 05:11 +0000
    Re: How can I make this piece of code even faster? Paul Rudin <paul.nospam@rudin.co.uk> - 2013-07-21 08:11 +0100
      Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 19:21 +1000
  Re: How can I make this piece of code even faster? Peter Otten <__peter__@web.de> - 2013-07-21 09:10 +0200
  Re: How can I make this piece of code even faster? Serhiy Storchaka <storchaka@gmail.com> - 2013-07-21 10:11 +0300
  Re: How can I make this piece of code even faster? Christian Gollwitzer <auriocus@gmx.de> - 2013-07-21 09:24 +0200
  Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-21 03:19 -0700
    Re: How can I make this piece of code even faster? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-21 10:31 +0000
      Re: How can I make this piece of code even faster? pablobarhamalzas@gmail.com - 2013-07-21 03:48 -0700
        Re: How can I make this piece of code even faster? Stefan Behnel <stefan_ml@behnel.de> - 2013-07-21 14:49 +0200
      Re: How can I make this piece of code even faster? Chris Angelico <rosuav@gmail.com> - 2013-07-21 20:48 +1000
    Re: How can I make this piece of code even faster? Michael Torrie <torriem@gmail.com> - 2013-07-21 09:27 -0600
  Re: How can I make this piece of code even faster? Joshua Landau <joshua@landau.ws> - 2013-07-21 12:39 +0100

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