NumPy

numpy.setdiff1d

numpy.setdiff1d(ar1, ar2, assume_unique=False)[source]

Find the set difference of two arrays.

Return the unique values in ar1 that are not in ar2.

Parameters
ar1array_like

Input array.

ar2array_like

Input comparison array.

assume_uniquebool

If True, the input arrays are both assumed to be unique, which can speed up the calculation. Default is False.

Returns
setdiff1dndarray

1D array of values in ar1 that are not in ar2. The result is sorted when assume_unique=False, but otherwise only sorted if the input is sorted.

See also

numpy.lib.arraysetops

Module with a number of other functions for performing set operations on arrays.

Examples

>>> a = np.array([1, 2, 3, 2, 4, 1])
>>> b = np.array([3, 4, 5, 6])
>>> np.setdiff1d(a, b)
array([1, 2])

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