title: VizStruct: exploratory visualization for gene expression profiling.
abstract: BACKGROUND
  DNA arrays provide a broad snapshot of the state of the cell by measuring the expression levels of thousands of genes simultaneously. Visualization techniques can enable the exploration and detection of patterns and relationships in a complex data set by presenting the data in a graphical format in which the key characteristics become more apparent. The dimensionality and size of array data sets however present significant challenges to visualization. The purpose of this study is to present an interactive approach for visualizing variations in gene expression profiles and to assess its usefulness for classifying samples.
  
  
  RESULTS
  The first Fourier harmonic projection was used to map multi-dimensional gene expression data to two dimensions in an implementation called VizStruct. The visualization method was tested using the differentially expressed genes identified in eight separate gene expression data sets. The samples were classified using the oblique decision tree (OC1) algorithm to provide a procedure for visualization-driven classification. The classifiers were evaluated by the holdout and the cross-validation techniques. The proposed method was found to achieve high accuracy.
  
  
  BACKGROUND
  Detailed mathematical derivation of all mapping properties as well as figures in color can be found as supplementary on the web page http://www.cse.buffalo.edu/DBGROUP/bioinformatics/supplementary/vizstruct. All programs were written in Java and Matlab and software code is available by request from the first author.
authors.affiliation: Department of Computer Science and Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA. lizhang@cse.buffalo.edu
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Aidong
authors.initials: A
authors.lastname: Zhang
authors.forename: Murali
authors.initials: M
authors.lastname: Ramanathan
mesh_terms: D000465:Algorithms; D016000:Cluster Analysis; D003196:Computer Graphics; D005260:Female; D015870:Gene Expression; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000235:genetics*; D009369:Neoplasms / Q000235:genetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D012984:Software; D014584:User-Computer Interface