Generate an additive function value based on a proportional influence variable into an additive function value
additive.function(ssn, VarName, afvName)
a SpatialStreamNetwork-class object
The name of the the variable that will be used to calculate the additive
function value. The data.frame
The name assigned to the column of additive function values, which are added to the ssn@data data.frame object, as well as the data.frames for the observed and prediction sites.
Calculating the additive function values (AFVs) is a two step process; first
VarName values are used to calculate the segment proportional
influences (PIs). Then the segment PI's are used to calculate the AFVs for
each line segment, observed site, and prediction site in the SpatialStreamNetwork-class
object. A detailed description of the segment PIs and the steps used to calculate
AFVs are provided in Peterson and Ver Hoef (2010; Appendix A). The
AFVs can also be calculated using the Spatial Tools for the Analysis of River
Systems (STARS), which is a custom ArcGIS (version 9.3.1) toolbox.
The SpatialStreamNetwork object,
ssn, with a new column named
included in the data.frames for the lines, observed sites, and prediction sites
to hold the AFVs.
Rohan Shah support@SpatialStreamNetworks.com
Peterson, E. E. and Ver Hoef, J. M. (2010) A mixed-model moving-average approach to geostatistical modeling in stream networks. Ecology 91(3), 644–651.
Peterson E.E.(2011)STARS: Spatial Tools for the Analysis of River Systems: A tutorial. CSIRO Technical Report EP111313. 42p.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
library(SSN) #for examples, copy MiddleFork04.ssn directory to R's temporary directory copyLSN2temp() # NOT RUN # Create a SpatialStreamNetork object that also contains prediction sites #mf04p <- importSSN(paste0(tempdir(),'/MiddleFork04.ssn'), # predpts = "pred1km", o.write = TRUE) #use mf04p SpatialStreamNetwork object, already created data(mf04p) #for examples only, make sure mf04p has the correct path #if you use importSSN(), path will be correct mf04p <- updatePath(mf04p, paste0(tempdir(),'/MiddleFork04.ssn')) #Calculate an additive function value based on an existing column. names(mf04p@data) mf04p <- additive.function(mf04p, "h2oAreaKm2", "areaAFV") #notice that a column called afvArea was already included, and "areaAFV" replicates it # in the lines data head(mf04p@data) # and in the observed points data head(getSSNdata.frame(mf04p)) # and in the prediction points data head(getSSNdata.frame(mf04p, "pred1km"))
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.