Remove consecutive duplicates in a NumPy array

by 
a[np.insert(np.diff(a).astype(np.bool), 0, True)]
Out[99]: array([0, 1, 3, 2, 3])

The general idea is to use diff to find the difference between two consecutive elements in the array. Then we only index those which give non-zero differences elements. But since the length of diff is shorter by 1. So before indexing, we need to insert the True to the beginning of the diff array.

Explanation:

In [100]: a
Out[100]: array([0, 0, 1, 3, 2, 2, 3, 3])

In [101]: diff = np.diff(a).astype(np.bool)

In [102]: diff
Out[102]: array([False,  True,  True,  True, False,  True, False], dtype=bool)

In [103]: idx = np.insert(diff, 0, True)

In [104]: idx
Out[104]: array([ True, False,  True,  True,  True, False,  True, False], dtype=bool)

In [105]: a[idx]
Out[105]: array([0, 1, 3, 2, 3])

More Related Contents:

  1. Group duplicate column IDs in pandas dataframe
  2. How to calculate rolling / moving average using python + NumPy / SciPy?
  3. String concatenation of two pandas columns
  4. Intuition and idea behind reshaping 4D array to 2D array in NumPy
  5. Find column name in pandas that matches an array
  6. How to count the occurrence of certain item in an ndarray?
  7. Reshape an array in NumPy
  8. How do I compute derivative using Numpy?
  9. binning data in python with scipy/numpy
  10. How do I count the occurrence of a certain item in an ndarray?
  11. Transform a set of numbers in numpy so that each number gets converted into a number of other numbers which are less than it
  12. Calculating Pearson correlation and significance in Python
  13. ValueError: could not broadcast input array from shape (224,224,3) into shape (224,224)
  14. Missing data, insert rows in Pandas and fill with NAN
  15. numpy array concatenate: “ValueError: all the input arrays must have same number of dimensions”
  16. How to split a numpy array in fixed size chunks with and without overlap?
  17. reading v 7.3 mat file in python
  18. Duplicate each member in a list [duplicate]
  19. Efficient distance calculation between N points and a reference in numpy/scipy
  20. Numpy: find index of the elements within range
  21. NumPy: Logarithm with base n
  22. Change values on matplotlib imshow() graph axis
  23. Duplicating model instances and their related objects in Django / Algorithm for recusrively duplicating an object
  24. How is numpy’s fancy indexing implemented?
  25. Convert row vector to column vector in NumPy
  26. How can I slice each element of a numpy array of strings?
  27. Add single element to array in numpy
  28. Plot NetworkX Graph from Adjacency Matrix in CSV file
  29. What is the Big O Complexity of Reversing the Order of Columns in Pandas DataFrame?
  30. How to include constraint to Scipy NNLS function solution so that it sums to 1

Leave a Comment