How to return 0 with divide by zero

by

In numpy v1.7+, you can take advantage of the “where” option for ufuncs. You can do things in one line and you don’t have to deal with the errstate context manager.

>>> a = np.array([-1, 0, 1, 2, 3], dtype=float)
>>> b = np.array([ 0, 0, 0, 2, 2], dtype=float)

# If you don't pass `out` the indices where (b == 0) will be uninitialized!
>>> c = np.divide(a, b, out=np.zeros_like(a), where=b!=0)
>>> print(c)
[ 0.   0.   0.   1.   1.5]

In this case, it does the divide calculation anywhere ‘where’ b does not equal zero. When b does equal zero, then it remains unchanged from whatever value you originally gave it in the ‘out’ argument.

More Related Contents:

  1. Sorting arrays in NumPy by column
  2. How to access the ith column of a NumPy multidimensional array?
  3. Python/NumPy first occurrence of subarray
  4. Concatenating two one-dimensional NumPy arrays
  5. Numpy matrix to array
  6. Reshape an array in NumPy
  7. Frequency counts for unique values in a NumPy array
  8. Selecting specific rows and columns from NumPy array
  9. How do I create an empty array and then append to it in NumPy?
  10. NumPy array initialization (fill with identical values)
  11. Immutable numpy array?
  12. How to get a list of all indices of repeated elements in a numpy array
  13. Binary random array with a specific proportion of ones?
  14. How to split a numpy array in fixed size chunks with and without overlap?
  15. Efficient distance calculation between N points and a reference in numpy/scipy
  16. Compress numpy arrays efficiently
  17. Add multiple values to one numpy array index
  18. Index 2D numpy array by a 2D array of indices without loops
  19. Flattening a list of NumPy arrays?
  20. Element-wise string concatenation in numpy
  21. Fastest pairwise distance metric in python
  22. Fastest save and load options for a numpy array
  23. Partition array into N chunks with Numpy
  24. Numpy Vector (N,1) dimension -> (N,) dimension conversion
  25. How is numpy’s fancy indexing implemented?
  26. Convert row vector to column vector in NumPy
  27. How can I slice each element of a numpy array of strings?
  28. Efficient dot products of large memory-mapped arrays
  29. Mapping a NumPy array in place
  30. numpy array row major and column major

Leave a Comment