title: How to concatenate 1000 images vertically using for loop in python?
body: <p>I want to concatenate vertically a lot of images. I used <code>skimage</code> to read images then in each iteration <code>io</code> read image and <code>vconcat</code> concatenate the new image on the old image vertically. The result of my code didn't concatenate the images, just combine the images. Any ideas how to make each image in each iteration concatenate vertically on each other?</p>
  <p>I want to concatenate the first image and the second image vertically:</p>
  <p><a href="https://i.stack.imgur.com/KofCB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KofCB.png" alt="fist image" /></a></p>
  <p><a href="https://i.stack.imgur.com/hZVqA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hZVqA.png" alt="second image" /></a></p>
  <p>but I got this result:</p>
  <p><a href="https://i.stack.imgur.com/ucxve.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ucxve.png" alt="result" /></a></p>
  <p><a href="https://i.stack.imgur.com/bwj6W.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bwj6W.png" alt="enter image description here" /></a></p>
  <pre><code>data = []
  if nSpectogram &lt; 3765:
      for k in range(0, 21):
          path = io.imread('E:\\wavelet\\spectrograms\\paz05\\'+'spec_'+isPreictal+'_'+str(nSpectogram+1)+'_'+str(k+1)+'.png')
          im_v_array = np.array(im_v)
          data.append(path)
      res = np.concatenate(data)
      plt.imshow(res, cmap='inferno', aspect='auto', interpolation='nearest')
  </code></pre>