title: Use lambda with multi input with numpy.apply_along_axis
body: <p>Here is my code:</p>
  <pre><code># 'a' is a 3D array which is the RGB data
  a = np.array([[[1, 2, 3], [4, 5, 6]], [[4, 5, 6], [1, 2, 3]]])
  # I want to do some calculate separately on R, G and B
  np.apply_along_axis(lambda r, g, b: r * 0.5 + g * 0.25 + b * 0.25, axis=-1, arr=a)
  
  # my target output is: [[1.75, 4.75], [4.75, 1.75]]
  </code></pre>
  <p>But the above way will give me error, missing 2 required positional arguments.</p>
  <p>I have tried to do like this:</p>
  <pre><code>np.apply_along_axis(lambda x: x[0] * 0.5 + x[1] * 0.25 + x[2] * 0.25, axis=-1, arr=a)
  </code></pre>
  <p>It works but every time when I need to do computation on the array element, I need to type the index, it is quite redundant. Is there any way that I can pass the array axis as multi iuputs to the lambda when using np.apply_along_axis?</p>