Linked Questions

2 votes
1 answer
4k views

K-means with high dimensional data [duplicate]

I read in many places that k-means clustering algorithm does not perform well when dealing with multidimensional binary data (so vectors whose entries are zero or one). Intuitively, it is pretty ...
445 votes
5 answers
177k views

How to understand the drawbacks of K-means

K-means is a widely used method in cluster analysis. In my understanding, this method does NOT require ANY assumptions, i.e., give me a dataset and a pre-specified number of clusters, k, and I just ...
KevinKim's user avatar
  • 6,919
360 votes
8 answers
165k views

Why is Euclidean distance not a good metric in high dimensions?

I read that 'Euclidean distance is not a good distance in high dimensions'. I guess this statement has something to do with the curse of dimensionality, but what exactly? Besides, what is 'high ...
teaLeef's user avatar
  • 3,817
110 votes
13 answers
41k views

Explain "Curse of dimensionality" to a child

I heard many times about curse of dimensionality, but somehow I'm still unable to grasp the idea, it's all foggy. Can anyone explain this in the most intuitive way, as you would explain it to a child,...
Kobe-Wan Kenobi's user avatar
43 votes
6 answers
14k views

Examples of PCA where PCs with low variance are "useful"

Normally in principal component analysis (PCA) the first few PCs are used and the low variance PCs are dropped, as they do not explain much of the variation in the data. However, are there examples ...
Michael's user avatar
  • 433
40 votes
2 answers
41k views

How to use both binary and continuous variables together in clustering?

I need to use binary variables (values 0 & 1) in k-means. But k-means only works with continuous variables. I know some people still use these binary variables in k-means ignoring the fact that k-...
GeorgeOfTheRF's user avatar
23 votes
4 answers
5k views

Does "curse of dimensionality" really exist in real data?

I understand what is "curse of dimensionality", and I have done some high dimensional optimization problems and know the challenge of the exponential possibilities. However, I doubt if the "curse of ...
Haitao Du's user avatar
  • 37.3k
18 votes
4 answers
16k views

What is the purpose of row normalization

I understand the reasoning behind column normalization, as it causes features to be weighted equally, even if they are not measured on the same scale - however, often in the nearest neighbour ...
curiosity_delivers's user avatar
4 votes
4 answers
2k views

PCA, dimensionality, and k-means results: reaction to duplicating of variables

There are many excellent conversations on CV about the curse of dimensionality when applied to methods like k-means. The answer in the same post and other research (e.g., the paper titled "When Is ‘...
Krrr's user avatar
  • 520
1 vote
1 answer
277 views

Intrinsic dimensionality and density-based clustering

I’ve got several thousand observations in 350-dimensional space, in a relatively sparse matrix (median observation has 11 non-zero dimensions). I'm using a density-based clustering algorithm, DBSCAN, ...
herfa's user avatar
  • 41
2 votes
1 answer
124 views

K means clustering breakup---galaxy spectrum data set

I have a spectrum data set (total 22000). Similar to an electronic wave data, two dimensional (Flux vs Wavelength). A typical set of wavelength plot looks like below Now I am doing kmeans on this ...
Ayan Mitra's user avatar
1 vote
1 answer
339 views

Unsupervised learning: How to identify differences between clusters?

I'm learning about unsupervised learning and I tried to use KMeans, AgglomerativeClustering and DBSCAN on the same datase. The result was ok, they seems to work fine according silhouette_score() ...
Antonio Caipora's user avatar
0 votes
0 answers
273 views

K-means: why reduce dimensions first? [duplicate]

I'm a bit confused about the usefulness of reducing dimensions before doing a k-means clustering. Suppose you want to apply k-means to a set points $(x_i)$ with high dimension. You want to minimize ...
Benoit Sanchez's user avatar