np.union1d() for union in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does np.union1d() do in NumPy?

np.union1d() returns the sorted unique values that are in either of two input arrays. It combines both arrays without duplicates.

beginner

How does np.union1d() handle duplicate values within the input arrays?

It removes duplicates and returns only unique values from both arrays combined.

beginner

What is the output type of np.union1d()?

The output is a NumPy array containing sorted unique elements from both input arrays.

beginner

Write a simple example of np.union1d() with arrays [1, 2, 3] and [3, 4, 5].

<pre>import numpy as np
arr1 = np.array([1, 2, 3])
arr2 = np.array([3, 4, 5])
result = np.union1d(arr1, arr2)
print(result)  # Output: [1 2 3 4 5]</pre>

beginner

Why is np.union1d() useful in data science?

It helps combine datasets or lists by merging unique values, which is useful for data cleaning and analysis.

What does np.union1d() return when given two arrays?

A Only values common to both arrays

B The first array unchanged

C All values including duplicates from both arrays

D Sorted unique values from both arrays combined

np.union1d() returns sorted unique values from both arrays combined, like a set union.

If arr1 = [1, 2, 2] and arr2 = [2, 3], what is np.union1d(arr1, arr2)?

A [1, 2, 2, 3]

B [2, 3]

C [1, 2, 3]

D [1, 3]

Duplicates are removed, so the union is [1, 2, 3].

Which of these is NOT true about np.union1d()?

A It modifies the original arrays

B It removes duplicates

C It combines values from both arrays

D It sorts the output array

np.union1d() does not change the original arrays; it returns a new array.

What data type does np.union1d() return?

A Tuple

B NumPy array

C List

D Set

The function returns a NumPy array with unique sorted elements.

Which NumPy function is best to combine two arrays and keep only unique sorted values?

A np.union1d()

B np.intersect1d()

C np.concatenate()

D np.append()

np.union1d() combines arrays and returns unique sorted values.

Explain how np.union1d() works and give a simple example.

Think about how sets work in math.

Why might you use np.union1d() in data science projects?

Consider cleaning and combining data.