Compute centers of the interval
centers.interval(sym.data)Centers of teh intervals.
Symbolic interval data table.
Jorge Arce.
Arce J. and Rodriguez O. (2015) 'Principal Curves and Surfaces to Interval Valued Variables'. The 5th Workshop on Symbolic Data Analysis, SDA2015, Orleans, France, November.
Hastie,T. (1984).Principal Curves and Surface. Ph.D Thesis Stanford University.
Hastie,T. & Weingessel,A. (2014). princurve - Fits a Principal Curve in Arbitrary Dimension.R package version 1.1--12 http://cran.r-project.org/web/packages/princurve/index.html.
Hastie,T. & Stuetzle, W. (1989). Principal Curves. Journal of the American Statistical Association, Vol. 84-406, 502--516.
Hastie, T., Tibshirani, R. & Friedman, J. (2008). The Elements of Statistical Learning; Data Mining, Inference and Prediction. Springer, New York.
sym.interval.pc