Questions tagged [unsupervised-learning]

Finding hidden (statistical) structure in unlabelled data, including clustering and feature extraction for dimensionality reduction.

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21 views

Techniques to measure similarities between instances and a dataset

I'd like to get a similarity measure between my dataset and a set of instances. For example, let's say I have a dataset with 4 features and n rows - ...
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1answer
75 views

unsupervised anomaly detection on sparse data

Given that I have a very sparse data matrix with continuous features, like this dataframe for example ...
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1answer
32 views

Confused between K-Means and Hierarchical Clustering for 9 different categories

I am trying to classify 9 different species of elephants into clusters using unsupervised learning. I have the following data about them: Their height Eye Colour Sound they produce in decibel (dB) I ...
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7 views

Is there a machine learning method for matching similar groupings?

I have a problem where I have rows/samples that are grouped together and each sample has a specific label (my data is genetic with genes being the samples and they are grouped together in the genome ...
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11 views

Is it viable to use ML models sequentially in a pipeline?

I have a machine learning model that predicts whether a gene is likely to cause a disease (the prediction is a probability score for a gene between 0 to 1, so a 1 score gene causes the disease and a 0 ...
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13 views

hierarchical clustering with categorical data

I have a dataset of 10K patients (row variables) with 10 disease conditions (such as heart condition, asthma, diabetes etc) along the columns. All the disease conditions are binary variables (yes/no). ...
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15 views

Outlier detection using 2D spatial information

I have a list of sensor measurements for air quality with geo-coordinates, and I would like to implement outlier detection. The list of sensors is relatively small (~50). The air quality can gradually ...
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22 views

Extract Keyword/Concept From Column Description Using NLP

Suppose in my database, each table has a description associated with each column and I want to further extract keyword or key concept from the description. For example, mean of transaction amount in ...
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7 views

How to determine a binary classifier threshold for unsupervised algorithms?

I am trying to create a model that can distinguish between normal and anomalous data. The training dataset contains non-anomalous data only. I am using an autoencoder that gets trained on this data to ...
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21 views

Is Normalized Mutual Info Score equivalent to V-measure when normalized by arithmetic mean

According to sklearn.metrics.v_measure_score, it says This score is identical to normalized_mutual_info_score with the 'arithmetic' option for averaging. In the ...
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10 views

General implications of low entropy for a dataset

I am fairly familiar with entropy, which quantifies uncertainty/surprisal of a random variable. In my case, I have a corpus where I can use empirical word frequencies to estimate entropy of the entire ...
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1answer
38 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 ...
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23 views

K-Means Clustering Problem in large 3D image CAD datasets

I have 1 million unclassified cad images in one folder and I need to cluster those images according to its similarity in 350 cluster folders, i.e k=350. Out of 350 folders after clustering, There are ...
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26 views

Clustering algorithm for a coordinate-based matrix

I have $1000$ scenarios, each of which is composed of $5$ users' coordinates $(x_i,y_i), \forall i \in \{1,\dots,5\}$. Now, based on users' coordinates, I want to cluster these $1000$ scenarios into ...
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6 views

Explanation of Excess Mass(EM)

I was researching on evaluation metrics to understand the performance of unsupervised anomaly detection algorithms and I came across this paper The author suggests that EM and MV based numerical ...
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9 views

Clustering DBSCAN's parameter Epsilon: How is eps related to scale of data being clustered?

How is scale of eps related to data to be clustered in DBSCAN? e.g. in image of 1024x1024, we have points as: ...
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11 views

Best way to suggest 'n' number of users based on demographic, interests data

I have to build a recommendation engine which suggests 'n' number of similar users to a user. I tried to implement this in user-user recommendation system methodology and unsupervised learning. Theres ...
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3answers
51 views

Unsupervised Anomaly Detection with groups

Let's say we are a bank and are interested in catching fraudulent customers. We gather ~100.000 independent samples of 40 independent variables and 4 are behavioral variables (what a customer does). ...
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12 views

autoencoders for radiographs - do watermarks affect the performance considerably

I have to implement an autoencoder to reconstruct the input radiographs and do unsupervised feature learning in the process. However, the radiographs that I have contain some watermarks like X-ray ...
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18 views

How can I cluster sequential data?

Suppose that I have a sequence of vectors $y_n \in \mathbb{R}^m$ for $n \in \{1, \dots, N\}$. My goal is to divide $y_n$ in $K$ clusters and want my clusters to satisfy the following conditions: Each ...
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1answer
40 views

is k-means generalizable at any distance? [duplicate]

The classical version of k-means uses the Euclidean distance in the first step, and the arithmetic mean (the value center) in the second step. Is k-means generalizable to other distances and other ...
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1answer
14 views

Why doesn't t-SNE need the labels before visualization?

In the original Maaten and Hinton paper, they explicitly say that the class membership is not used by the t-SNE calculations, only for picking colors in the plot. For all of the data sets, there is ...
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7 views

What is the statistical relevance of gamma in k-prototypes algorithm and why is it related to the standard deviation of the numeric columns?

The k-prototype algorithm uses gamma to provide weight to the categorical features. I have a few queries regarding it : Why is there no upper limit to it? Should it not be (1-gamma) such that gamma ...
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19 views

Fixing the parameters of the variational distribution in Expectation-Maximization

Consider directed graphical model $z \to x$ (with $z$ unobserved and $x$ observed). The evidence lower bound on the log-likelihood $\log p(x) = \log \sum_z p(x, z; \theta)$ for parameters $\theta$ (...
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9 views

Best practice/Ideas for clustering Event Sequence Embeddings?

My dataset consist of around 40 000 samples of event sequences. Sample of data [[Event 1, Event 2, Event 4, Event 5], [Event 1, Event 3, Event 4], [...]] I ...
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19 views

What is the meaning of noise in a dataset with no dependant variable?

My understanding of noise & signal comes from the context of bias-variance tradeoff in supervised methods. But given a dataset with no dependant variable, how do you define noise? & how do you ...
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11 views

Updating an unsupervised model but retaining similarity

In my example I am using topic modelling (specifically a version of LDA) although I think avenues for exploring this could relate to other unsupervised techniques like clustering. I train a model and ...
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2answers
38 views

How can PCA maximise variance after I standardise all predictor variance = 1?

I have been reading about Principal Components Analysis, and I think it is in general trying to extract as much "variance" out of the predictors $ \vec{X} = (X_1, X_2, ..., X_n)$ by ...
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17 views

Latest research and explanation on how semi-supervised learning is performing better than supervised?

So in AAAI 2020 also semi-supervised learning is given the push. There are some intuitive reasoning provided by people but since the research is so fast, I wanted to know actually what is the latest ...
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19 views

Evaluation method for outlier detection with a data that has no labels

I am applying an unsupervised outlier detection model called isolation-Forest to detect outliers using unlabelled time-series data. I do not have labels that distinguish a true outlier from a false ...
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9 views

Clustering Algorithms for News Aggregator

I'm working on a news aggregator, and I am trying to get very nice clusters for similar articles. I'm only working with a few hundred articles so speed is not a concern for me. I already have plans as ...
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17 views

Compare similarity/dissimilarity b/w 2 clustering results from different datasets

So I am trying to find out how similar are 2 clustering results (hierarchial). 1st dataset comprises of 10 features. 2nd dataset comprises of these 10 features plus 5 additional features. So my basic ...
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1answer
32 views

Auto-encoders' learning process and overfitting

Reading about autoencoders from Ian Goodfellow's deep learning book, and they made this statement about autoencoders learning process on page 494: "Unfortunately, if the encoder and the decoder ...
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1answer
28 views

Definition of boundary points in DBSCAN

If I understand correctly, DBSCAN is the following method of decomposing a set, which has parameters $\epsilon$ and $k$. Given a set $E$ of points in $\mathbb R^n$, consider the graph $G$ whose ...
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2k views

Are all Machine Learning algorithms divided into Classification and Regression, not just supervised learning?

I'm newbie in AI I know that Supervised Learning algorithms are divided into Classification and Regression algorithms. But is that true of all machine learning algorithms, not just Supervised Learning?...
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8 views

Reverse engineer unsupervised algo using supervised one

Let's say that through some unknown process, each row in a dataset is labelled with an integer between 1 to 10 inclusive. Now, if I run random forest for example, and get a promising result for ...
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1answer
54 views

Can a Gaussian Mixture model be fit with a continuous response variable?

Does the Gaussian Mixture model require binary and multiclass response/target variable (classification), or can the target vector consist of all real numbers (continuous variable, regression)? Why is ...
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7 views

Prerequisites/Checks for performing clustering

What are the checks that should be done on our data before performing clustering? Like how to check whether the dataset contains clusters of equal size/density or the clusters present in the dataset ...
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41 views

When to use K-Medoids instead of K-means

When it's better to use K-Medoids rather than K-Means? Can anybody give some examples of dataset for the same?
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1answer
117 views

Limitations of K-Means Clustering [duplicate]

I was going through a document of Western Michigan University to understand the limitations of K-means clustering algorithms. Below is the link: https://cs.wmich.edu/alfuqaha/summer14/cs6530/lectures/...
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20 views

How do you train a clustering model?

This should've been a pretty simple question, but I still have a few questions so I decided to bring the discussion here. The thing is, I have a group of products, and the historical dataset looks ...
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1answer
80 views

Is Anomaly Detection Supervised or Un-supervised?

AFAIK - One way to process data faster and more efficiently is to detect abnormal events, changes, or shifts in datasets. Anomaly detection, also known as outlier detection is the process of ...
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2answers
97 views

Feature extraction in deep neural networks

From many definitions that I read, I concluded that a DNN (deep neural network) is an ANN (artificial neural network) that have more than one hidden layer. Knowing that CNN (convolutional neural ...
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13 views

Gaussian Mixture Model Clustering - cluster means are assigned to a different cluster

I ran a gaussian mixture model with 7 clusters on my data. My data has been PCA transformed with 200 components. Then I extracted the means of each cluster and applied the predict_proba function on ...
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1answer
22 views

What statistical tests or machine learning techniques would be best for discrete variables with many levels?

I have a dataframe with 20 categorical variables, each with 30+ levels. As a result I don't have a target variable on hand per-say but I would like to use statistical techniques or machine learning to ...
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23 views

Why is my training unstable?

I am training a Variational autoencoder with and without data labels. When I use labels (blue line), validation error decreases with epochs but without labels (orange line) the training is unstable. ...
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1answer
32 views

Does automatic feature selection for clustering helps with finding meaningful clusters?

The objective of clustering is to find interesting groups in data. My question is, whether feature selection can substantially help with this objective. I understand feature selection can remove ...
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29 views

How to achieve good clustering results in subsequence time series clustering with DBSCAN?

I want to find patterns in a time series and use clustering for that. Before I cluster, I create subsequences from the time series using a sliding window approach. (STS-clustering) So far I have tried ...
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1answer
16 views

Differentiability in Generative Adversarial Networks

I've got some questions about the differentiability condition of GAN's, i.e. both G and D need to be differentiable wrt. their inputs and the parameters describing them. It's of more mathematical ...
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25 views

stepwise clustering

Assume that we have 3 features in our dataset and we aim to cluster them. Assume that first two variables are in the same scale and have a "similar nature" and the third one has totally different ...

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