Package 'openair'

polarCluster 87ValueNote that there are no automatic ways in ensuring the most appropriate number of clusters as thisis application dependent. However, there is often a-priori information available on what differentfeatures in polar plots correspond to. Nevertheless, the appropriateness of different clusters is bestdetermined by post-processing the data. The Carslaw and Beevers (2012) paper discusses theseissues in more detail.Note that unlike most other openair functions only a single type “default” is allowed.As well as generating the plot itself, polarCluster also returns an object of class “openair”. Theobject includes three main components: call, the command used to generate the plot; data, theoriginal data frame with a new field cluster identifying the cluster; and plot, the plot itself. Notethat any rows where the value of pollutant is NA are ignored so that the returned data frame mayhave fewer rows than the original.An openair output can be manipulated using a number of generic operations, including print, plotand summary. See openair.generics for further details.Author(s)David CarslawReferencesCarslaw, D.C., Beevers, S.D, Ropkins, K and M.C. Bell (2006). Detecting and quantifying aircraftand other on-airport contributions to ambient nitrogen oxides in the vicinity of a large internationalairport. Atmospheric Environment. 40/28 pp 5424-5434.Carslaw, D.C. and S.D. Beevers (2012). Characterising and understanding emission sources usingbivariate polar plots and k-means clustering. Environmental Modelling & Software. Submitted.See AlsopolarPlotExamples## Not run:# load example data from packagedata(mydata)## plot 2-8 clusters. Warning! This can take several minutes...\dontrun{polarCluster(mydata, pollutant = "nox", n.clusters = 2:8)}# basic plot with 6 clustersresults