18,078 research outputs found
Unsupervised spectral sub-feature learning for hyperspectral image classification
Spectral pixel classification is one of the principal techniques used in hyperspectral image (HSI) analysis. In this article, we propose an unsupervised feature learning method for classification of hyperspectral images. The proposed method learns a dictionary of sub-feature basis representations from the spectral domain, which allows effective use of the correlated spectral data. The learned dictionary is then used in encoding convolutional samples from the hyperspectral input pixels to an expanded but sparse feature space. Expanded hyperspectral feature representations enable linear separation between object classes present in an image. To evaluate the proposed method, we performed experiments on several commonly used HSI data sets acquired at different locations and by different sensors. Our experimental results show that the proposed method outperforms other pixel-wise classification methods that make use of unsupervised feature extraction approaches. Additionally, even though our approach does not use any prior knowledge, or labelled training data to learn features, it yields either advantageous, or comparable, results in terms of classification accuracy with respect to recent semi-supervised methods
Taming Wild High Dimensional Text Data with a Fuzzy Lash
The bag of words (BOW) represents a corpus in a matrix whose elements are the
frequency of words. However, each row in the matrix is a very high-dimensional
sparse vector. Dimension reduction (DR) is a popular method to address sparsity
and high-dimensionality issues. Among different strategies to develop DR
method, Unsupervised Feature Transformation (UFT) is a popular strategy to map
all words on a new basis to represent BOW. The recent increase of text data and
its challenges imply that DR area still needs new perspectives. Although a wide
range of methods based on the UFT strategy has been developed, the fuzzy
approach has not been considered for DR based on this strategy. This research
investigates the application of fuzzy clustering as a DR method based on the
UFT strategy to collapse BOW matrix to provide a lower-dimensional
representation of documents instead of the words in a corpus. The quantitative
evaluation shows that fuzzy clustering produces superior performance and
features to Principal Components Analysis (PCA) and Singular Value
Decomposition (SVD), two popular DR methods based on the UFT strategy
A transfer-learning approach to feature extraction from cancer transcriptomes with deep autoencoders
Publicado en Lecture Notes in Computer Science.The diagnosis and prognosis of cancer are among the more
challenging tasks that oncology medicine deals with. With the main aim
of fitting the more appropriate treatments, current personalized medicine
focuses on using data from heterogeneous sources to estimate the evolu-
tion of a given disease for the particular case of a certain patient. In recent
years, next-generation sequencing data have boosted cancer prediction by
supplying gene-expression information that has allowed diverse machine
learning algorithms to supply valuable solutions to the problem of cancer
subtype classification, which has surely contributed to better estimation
of patient’s response to diverse treatments. However, the efficacy of these
models is seriously affected by the existing imbalance between the high
dimensionality of the gene expression feature sets and the number of sam-
ples available for a particular cancer type. To counteract what is known
as the curse of dimensionality, feature selection and extraction methods
have been traditionally applied to reduce the number of input variables
present in gene expression datasets. Although these techniques work by
scaling down the input feature space, the prediction performance of tradi-
tional machine learning pipelines using these feature reduction strategies
remains moderate. In this work, we propose the use of the Pan-Cancer
dataset to pre-train deep autoencoder architectures on a subset com-
posed of thousands of gene expression samples of very diverse tumor
types. The resulting architectures are subsequently fine-tuned on a col-
lection of specific breast cancer samples. This transfer-learning approach
aims at combining supervised and unsupervised deep learning models
with traditional machine learning classification algorithms to tackle the
problem of breast tumor intrinsic-subtype classification.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
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