rtop: An R package for interpolation of data with a variable spatial support, with an example from river networks

Geostatistical methods have been applied only to a limited extent for spatial interpolation in applications where the observations have an irregular support, such as runoff characteristics along a river network and population health data. Several studies have shown the potential of such methods, but these developments have so far not led to easily accessible, versatile, easy to apply and open source software. Based on the top-kriging approach suggested by Skøien et al. (2006), we will here present the package rtop, which has been implemented in the statistical environment R (R Core Team, 2013). Taking advantage of the existing methods in R for analysis of spatial objects (Bivand et al., 2013), and the extensive possibilities for visualizing the results, rtop makes it easy to apply geostatistical interpolation methods when observations have a non-point spatial support. The package also offers integration with the intamap package for automatic interpolation and the possibility to run rtop through a Web Service. & 2014 Elsevier Ltd. All rights reserved.