[SciPy-User] [SciPy-user] Avoiding inner for loops

[Issa Karambal]

If you do not want to use any loop, you might try this


params = param1*param2*param3
ans = data1+data2*params[:, None]
ss = np.sum(obs - ans, axis=1)**2

On 19 August 2012 20:36, Issa Karambal <issa at aims.ac.za> wrote:

> Hi,
> This will help. You do not need to have  'fake_model' function
>
> ss = []
> params = param1*param2*param3
> ans = data1+data2*params[:, None]
> for i in range(0,len(ans)):
>      ss.append( np.sum( obs-ans[i] )**2 )
>
>
> On 19 August 2012 08:56, mdekauwe <mdekauwe at gmail.com> wrote:
>
>>
>> Hi,
>>
>> I need to avoid (at least) two inner for loops in what I am trying to do
>> otherwise my processing takes forever. What is the best way to transfer
>> what
>> I am doing into a more "numpy way"? Essentially I am trying to call a
>> model
>> again for various different parameter combinations. The example is
>> fictional, by the grid_size would ideally grow > 500 and by doing so the
>> processing speed becomes very slow the way I have set things up..
>>
>> thanks.
>>
>> example.
>>
>>
>> import numpy as np
>>
>> def fake_model(data1, data2, p1, p2, p3):
>>     """ complete nonsense """
>>     return data1 + data2 * p1 * p2 * p3
>>
>> data1 = np.random.rand(10) # the size of this arrays varies might be 10
>> might be 15 etc
>> data2 = np.random.rand(10) # the size of this arrays varies might be 10
>> might be 15 etc
>> obs = np.random.rand(10) # the size of this arrays varies might be 10
>> might
>> be 15 etc
>>
>> grid_size = 10 # Ideally this would be a large number
>> param1 = np.linspace(5.0, 350, grid_size)
>> param2 = np.linspace(5.0, 550, grid_size)
>> param3 = np.linspace(1E-8, 10.5, grid_size)
>> ss = np.zeros(0)
>>
>> for p1 in param1:
>>     for p2 in param2:
>>         for p3 in param3:
>>             ans = fake_model(data1, data2, p1, p2, p3)
>>
>>             ss = np.append(ss, np.sum(obs - ans)**2)
>>             print np.sum(obs - ans)**2
>> --
>> View this message in context:
>> http://old.nabble.com/Avoiding-inner-for-loops-tp34319609p34319609.html
>> Sent from the Scipy-User mailing list archive at Nabble.com.
>>
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>
>
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