Databases
StackOverflow2013
Postsdbo
POPython scipy.numpy.convolve and scipy.signal.fftconvolve different results
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POPython scipy.numpy.convolve and scipy.signal.fftconvolve different results
    primarykey
    data
    text
    <p>i am having 2 arrays (G and G_). They have the same shape and size and i want to convolve them. i found the numpy.convolve and fftconvolve. My Code is like:</p> <pre><code>foldedX = getFoldGradientsFFT(G, G_) foldedY = getFoldGradientsNumpy(G, G_) def getFoldGradientsFFT(G, G_): # convolve via scipy fast fourier transform X =signal.fftconvolve(G,G_, "same) X*=255.0/numpy.max(X); return X def getFoldGradientsNumpy(G, G_): # convolve via numpy.convolve Y = ndimage.convolve(G, G_) Y*=255.0/numpy.max(Y); return Y </code></pre> <p>But the results aren't the same. The result is like: Numpy.concolve()</p> <pre><code>[ 11.60287582 3.28262652 18.80395211 52.75829556 99.61675945 147.74124258 187.66178244 215.06160439 234.1907606 229.04221552] </code></pre> <p>scipy.signal.fftconvolve:</p> <pre><code>[ -4.88130620e-15 6.74371119e-02 4.91875539e+00 1.94250997e+01 3.88227012e+01 6.70322921e+01 9.78460423e+01 1.08486302e+02 1.17267015e+02 1.15691562e+02] </code></pre> <p>I thought the result is supposed to be the same, even if the two functions convolves with a different procedure?!</p> <hr> <p>i forgot to mention, that i want to convolve 2 2-dimensional arrays :S the arrays:</p> <pre><code>G = array([[1,2],[3,4]]) G_ = array([[5,6],[7,8]]) </code></pre> <p>the code</p> <pre><code>def getFoldGradientsFFT(G, G_): X =signal.fftconvolve(G,G_,"same") X=X.astype("int") X*=255.0/np.max(X); return X def getFoldGradientsNumpy(G, G_): # convolve via convolve old_shape = G.shape G = np.reshape(G, G.size) G_ = np.reshape(G_, G.size) Y = np.convolve(G, G_, "same") Y = np.reshape(Y,old_shape) Y = Y.astype("int") Y*=255.0/np.max(Y); return Y def getFoldGradientsNDImage(G, G_): Y = ndimage.convolve(G, G_) Y = Y.astype("int") Y *= 255.0/np.max(Y) return Y </code></pre> <p>the results:</p> <pre><code>getFoldGradientsFFT [[ 21 68] [ 93 255]] getFoldGradientsNumpy [[ 66 142] [250 255]] getFoldGradientsNDImage [[147 181] [220 255]] </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USBill the Lizard
    1. UStienbuiDE
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POPython scipy.numpy.convolve and scipy.signal.fftconvolve different results
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POPython scipy.numpy.convolve and scipy.signal.fftconvolve different results
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POPython scipy.numpy.convolve and scipy.signal.fftconvolve different results
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload