Multiple choices questions in Machine learning. Interview questions on machine learning, quiz questions for data scientist answers explained, machine learning exam questions, question bank in machine learning, Hierarchical agglomerative clustering, How to calculate the pairwise distance using single linkage? Complete linkage agglomerative clustering
Machine Learning MCQ  Hierarchical agglomerative clustering  single linkage and complete linkage
1. After three iterations of Hierarchical Agglomerative Clustering using Euclidean distance between points, we get the 3 clusters: C1 = {2, 4}, C2 = {7, 8} and C3 = {12, 14}. What is the distance between clusters C1 and C2 using Single Linkage and Complete Linkage?
a) 2, 2
b) 3, 4
c) 3, 6
d) 5, 6
Answer: (c) 3, 6
Single linkage In single linkage, we define the distance between two clusters as the minimum distance between any single data point in the first cluster and any single data point in the second cluster. On the basis of this definition of distance between clusters, at each stage of the process we combine the two clusters with the smallest single linkage distance. As per single linkage, d(C1, C2) = d({2, 4}, {7, 8}) = min(27, 28, 47, 48) = min(5, 6, 3, 4) = 3 Single linkage hierarchical clustering In singlelink (or single linkage) hierarchical clustering, we merge in each step the two clusters whose two closest members have the smallest distance (or: the two clusters with the smallest minimum pairwise distance).
Complete linkage In complete linkage, we define the distance between two clusters to be the maximum distance between any single data point in the first cluster and any single data point in the second cluster. On the basis of this definition of distance between clusters, at each stage of the process we combine the two clusters that have the smallest complete linkage distance. As per complete linkage, d(C1, C2) = d({2, 4}, {7, 8}) = max(27, 28, 47, 48) = max(5, 6, 3, 4) = 6 Complete linkage hierarchical clustering In completelink (or complete linkage) hierarchical clustering, we merge in each step the two clusters whose merger has the smallest diameter (or: the two clusters with the smallest maximum pairwise distance).

Related links:
Hierarchical agglomerative clustering
How is single link distance calculated?
How is complete linkage distance calculated?
What is single linkage method?
What is complete linkage method?
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