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196
votes
Clustering on the output of t-SNE
If we run t-SNE with a too small perplexity such as 20, we get more of these patterns that do not exist:
This will cluster e.g. with DBSCAN, but it will yield four clusters. … In: Proceedings of the 10th International Conference on Similarity Search and Applications (SISAP), Munich, Germany. 2017
First, we have this input data:
As you may guess, this is derived from a "color …
98
votes
Choosing the right linkage method for hierarchical clustering
Two most dissimilar cluster members can happen to be very much dissimilar in comparison to two most similar. Single linkage method controls only nearest neighbours similarity. … The metaphor of this build of cluster is type. …
97
votes
6
answers
171k
views
Why does k-means clustering algorithm use only Euclidean distance metric?
Is there a specific purpose in terms of efficiency or functionality why the k-means algorithm does not use for example cosine (dis)similarity as a distance metric, but can only use the Euclidean norm? … "(Non)Euclidean distance" may concern distance between two data points or distance between a data point and a cluster centre. Both ways have been attempted to address in the answers so far.] …
92
votes
How does a Support Vector Machine (SVM) work?
$\mathbf{w^T}$ is the transpose of $\mathbf{w}$, and $\|\mathbf{w}\| = \mathbf{w}^T\mathbf{w}$.
Let:
$\mathbf{x}$ be a feature vector (i.e., the input of the SVM). … cluster=469291847682573606&hl=en&as_sdt=0,22 ; http://www.chapelle.cc/olivier/pub/neco07.pdf …
89
votes
Accepted
How to tell if data is "clustered" enough for clustering algorithms to produce meaningful re...
the three clusters (krange) were dissolved across the samples, and the average clusterwise Jaccard similarity is > 0.95 for all clusters. … gamma, within sum of squares) for a range of cluster numbers (e.g., 2 to 10), repeat 100 or 500 times, and look at the boxplot of your statistic as a function of the number of cluster. …
77
votes
Accepted
How to select a clustering method? How to validate a cluster solution (to warrant the method...
I can imagine of a number dimensions or aspects of "rightness" of this or that clustering method:
Cluster metaphor. … Each clustering algorithm or subalgorithm/method implies its corresponding structure/build/shape
of a cluster. …
74
votes
Accepted
Why do we do matching for causal inference vs regressing on confounders?
You estimate the treatment effect using a simple linear regression of the outcome on the treatment and the covariates, including the matching weights in the regression and using a cluster-robust standard … This all centers on covariate balance, the similarity between covariate distributions across the treatment groups. …
69
votes
Accepted
Clustering a long list of strings (words) into similarity groups
It works on anything you can define the pairwise similarity on. Which you can get by multiplying the Levenshtein distance by -1. … cluster they are exemplar of):
have: chances, edit, hand, have, high
following: following
problem: problem
I: I, a, at, etc, in, list, of
possibly: possibly
cluster: cluster
word: For, and, for, long …
69
votes
Accepted
Hierarchical clustering with mixed type data - what distance/similarity to use?
The facets of Gower similarity ($GS$):
When all variables are quantitative (interval) then the coefficient is the range-normalized Manhattan distance converted into similarity. … A general coefficient of similarity and some of its properties // Biometrics, 1971, 27, 857-872
$^2$ Podani, J. …
61
votes
5
answers
38k
views
Apply word embeddings to entire document, to get a feature vector
I could use the word embedding to cluster the vocabulary of all words into a fixed set of clusters, say, 1000 clusters, where I use cosine similarity on the vectors as a measure of word similarity. … that are part of cluster $i$. …
58
votes
3
answers
115k
views
Clustering a long list of strings (words) into similarity groups
I need to cluster this word list, such that similar words, for example words with similar edit (Levenshtein) distance appears in the same cluster. … For example "algorithm" and "alogrithm" should have high chances to appear in the same cluster. …
54
votes
5
answers
67k
views
Dynamic Time Warping Clustering
What would be the approach to use Dynamic Time Warping (DTW) to perform clustering of time series? … I have read about DTW as a way to find similarity between two time series, while they could be shifted in time. Can I use this method as a similarity measure for clustering algorithm like k-means? …
53
votes
Comparing hierarchical clustering dendrograms obtained by different distances & methods
To compare the similarity of two hierarchical (tree-like) structures, measures based on cophenetic correlation idea are used. … If after the above precautions you continue to think that you want a measure of similarity between hierarchical classifications you might google on 'comparing of dendrograms' and 'comparing hierarchical …
49
votes
Accepted
Clustering with a distance matrix
The algorithm is called Clara in R, and is described in chapter 3 of Finding Groups in Data: An Introduction to Cluster Analysis. by Kaufman, L and Rousseeuw, PJ (1990). … In R you can take a look at the package cluster. All described algorithms are implemented there. See ?pam, ?clara, ?hclust, ... Check also the different implementation of the algorithm in ?kmeans. …
48
votes
8
answers
29k
views
How to do community detection in a weighted social network/graph?
The graph in question has approximately 3 million edges and each edge expresses the degree of similarity between the two vertices it connects. … In particular, in this dataset edges are individuals and vertices are a measure of the similarity of their observed behavior. …