anemones {spatstat.data}

Beadlet Anemones Data

Description

These data give the spatial locations and diameters of sea anemones (beadlet anemone Actinia equina) in a sample plot on the north face of a boulder, well above low tide level, at Quiberon (Bretagne, France) in May 1976.

The data were originally described and discussed by Kooijman (1979a). Kooijman (1979b) shows a hand-drawn plot of the original data. The data are discussed by Upton and Fingleton (1985) as Example 1.8 on pages 64–67.

The anemones dataset is taken directly from Table 1.11 of Upton and Fingleton (1985). The coordinates and diameters are integer multiples of an idiosyncratic unit of length. The boundary is a rectangle 280 by 180 units.

Usage

data(anemones)

Format

anemones is an object of class "ppp" representing the point pattern of anemone locations. It is a marked point pattern with numeric marks representing anemone diameter. See ppp.object for details of the format.

Units

There is some confusion about the correct physical scale for these data. According to Upton and Fingleton (1985), one unit in the dataset is approximately 0.475 cm. According to Kooijman (1979a, 1979b) and also quoted by Upton and Fingleton (1985), the physical size of the sample plot was 14.5 by 9.75 decimetres (145 by 97.5 centimetres). However if the data are plotted at this scale, they are too small for a rectangle of this size, and the appearance of the plot does not match the original hand-drawn plot in Kooijman (1979b). To avoid confusion, we have not assigned a unit scale to this dataset.

Source

Table 1.11 on pages 62–63 of Upton and Fingleton (1985), who acknowledge Kooijman (1979a) as the source.

References

Kooijman, S.A.L.M. (1979a) The description of point patterns. In Spatial and temporal analysis in ecology (ed. R.M. Cormack and J.K. Ord), International Cooperative Publishing House, Fairland, Maryland, USA. Pages 305–332.

Kooijman, S.A.L.M. (1979b) Inference about dispersal patterns. Acta Biotheoretica 28, 149–189.

Upton, G.J.G. and Fingleton, B. (1985) Spatial data analysis by example. Volume 1: Point pattern and quantitative data. John Wiley and Sons, Chichester.

Examples

  data(anemones)
  if(require(spatstat.geom)) {
  # plot diameters on same scale as x, y
  plot(anemones, markscale=1)
  }