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# scipy.ndimage.measurements.extrema

`scipy.ndimage.measurements.``extrema`(input, labels=None, index=None)

  Calculate the minimums and maximums of the values of an array at labels, along with their positions.

  Parameters : | input : ndarray Nd-image data to process. labels : ndarray, or None, optional Labels of features in input. If not None, must be same shape as input. index : None, int, or sequence of int, optional Labels to include in output. If None, all values where non-zero labels are used.
  Returns : | minimums, maximums : int or ndarray Values of minimums and maximums in each feature. min_positions, max_positions : tuple or list of tuples Each tuple gives the n-D coordinates of the corresponding minimum or maximum.

  See also

  `maximum`, `minimum`, `maximum_position`, `minimum_position`, `center_of_mass`

  Examples

      >>> a = np.array([[1, 2, 0, 0],
                        [5, 3, 0, 4],
                        [0, 0, 0, 7],
                        [9, 3, 0, 0]])
      >>> from scipy import ndimage
      >>> ndimage.extrema(a)
      (0, 9, (0, 2), (3, 0))

  Features to process can be specified using labels and index:

      >>> lbl, nlbl = ndimage.label(a)
      >>> ndimage.extrema(a, lbl, index=np.arange(1, nlbl+1))
      (array([1, 4, 3]),
       array([5, 7, 9]),
       [(0.0, 0.0), (1.0, 3.0), (3.0, 1.0)],
       [(1.0, 0.0), (2.0, 3.0), (3.0, 0.0)])

  If no index is given, non-zero labels are processed:

      >>> ndimage.extrema(a, lbl)
      (1, 9, (0, 0), (3, 0))

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