..here's a very illustrative R-Script example by Legendre & Borcard showing how a Nested ANOVA can be done by permutation.
30 May 2011
25 May 2011
When recording species abundance data you often have endless rows with species names and one gets swollen eyes from searching the right line for each data-entry. Therefore I made myself a handy xls-file to collect species abundance data.
In it a VBA-macro is called with a keybord short-cut which matches a species short name you type in the active cell and jumps to the line with that species, the search entry is deleted automatically and you are in the cell where you want to add data... (download).
There's no ArcGis-tool for calculating neighborhood-statistics for samplepoints based on raster-data: say you had a raster with presence/absence data of a given feature and for a set of samplepoints you wanted to know the feature's occurrence rate (percentage of cells with presence of that feature) in the samplepoints neighborhood, then you will find this model (saved in toolbox NESTPTS.tbx) useful.
23 May 2011
Here's an example how to conveniently summarize data with the cast function (package reshape). By the way you see how this could be done "in-conveniently" by hand. You also see how a for-loop works and how a matrix is constructed and filled. In addition this serves as an illustrative example how flexible "indexing" in R works, as seen in the below loop! (download data) (this example is adapted from https://stat.ethz.ch/pipermail/r-sig-ecology/2011-May/002174.html)
2 May 2011
Here's a set of historical species presence records of a certain geographical region (data-link). I wanted to manipulate / simplify strings (species names) and get an overview of the data....The tasks were to split genera and epitheta, to exclude species with specific strings included and to get rid of unwanted text (author names). For graphical presentation of the species record history I did a plot with segments indicating the first and last year of a species record: