🔢 NumPy Set Operations

NumPy provides a set of functions to perform set-like operations on arrays. These operations are element-wise, unique, and sorted by default, similar to Python sets but optimized for arrays.

✅ 1. Unique Elements (np.unique)

• Returns sorted unique elements

• Can also return indices, counts:

✅ 2. Intersection (np.intersect1d)

• Elements present in both arrays

✅ 3. Union (np.union1d)

• Combines all elements from both arrays without duplicates

✅ 4. Set Difference (np.setdiff1d)

• Returns elements present in first array but not in second

✅ 5. Symmetric Difference / XOR (np.setxor1d)

• Returns elements in arr1 or arr2 but not in both

✅ 6. Membership Testing (np.in1d)

• Checks element-wise if array1 elements are in array2

• Returns boolean array

✅ 7. Notes & Tips

• All results are sorted

• Ideal for finding unique items, overlaps, and differences

• Useful in data cleaning, analysis, and comparisons

🎯 Practice Exercises

1. Find unique elements of [1,2,2,3,3,4,5,5].

2. Find intersection and union of [1,2,3,4] and [3,4,5,6].

3. Find difference and symmetric difference of the same arrays.

4. Test membership of [1,2,3] in [2,3,4].