[R] function for cumulative occurrence of elements

From: Steven K Friedman <friedm69_at_msu.edu>
Date: Tue 28 Jun 2005 - 22:55:13 EST

Hello,

I have a data set with 9700 records, and 7 parameters.

The data were collected for a survey of forest communities. Sample plots (1009) and species (139) are included in this data set. I need to determine how species are accumulated as new plots are considered. Basically, I want to develop a species area curve.

I've included the first 20 records from the data set. Point represents the plot id. The other parameters are parts of the information statistic H'.

Using "Table", I can construct a data set that lists the occurrence of a species at any Point (it produces a binary 0/1 data table). From there it get confusing, regarding the most efficient approach to determining the addition of new and or repeated species occurrences.

ptcount <- table(sppoint.freq$species, sppoint.freq$Point)

 From here I've played around with colSums to calculate the number of species at each Point. The difficulty is determining if a species is new or repeated. Also since there are 1009 points a function is needed to screen every Point.

Two goals are of interest: 1) the species accumulation curve, and 2) an accumulation curve when random Points are considered.

Any help would be greatly appreciated.

Thank you
Steve Friedman

 Point species frequency point.list point.prop log.prop point.hprime
1 7 American elm 7 27 0.25925926 -1.3499267 0.3499810
2 7 apple 2 27 0.07407407 -2.6026897 0.1927918
3 7 black cherry 8 27 0.29629630 -1.2163953 0.3604134
4 7 black oak 1 27 0.03703704 -3.2958369 0.1220680
5 7 chokecherry 1 27 0.03703704 -3.2958369 0.1220680
6 7 oak sp 1 27 0.03703704 -3.2958369 0.1220680
7 7 pignut hickory 1 27 0.03703704 -3.2958369 0.1220680
8 7 red maple 1 27 0.03703704 -3.2958369 0.1220680
9 7 white oak 5 27 0.18518519 -1.6863990 0.3122961
10 9 black spruce 2 27 0.07407407 -2.6026897 0.1927918
11 9 blue spruce 2 27 0.07407407 -2.6026897 0.1927918
12 9 missing 12 27 0.44444444 -0.8109302 0.3604134
13 9 Norway spruce 8 27 0.29629630 -1.2163953 0.3604134
14 9 white spruce 3 27 0.11111111 -2.1972246 0.2441361
15 12 apple 2 27 0.07407407 -2.6026897 0.1927918
16 12 black cherry 1 27 0.03703704 -3.2958369 0.1220680
17 12 black locust 1 27 0.03703704 -3.2958369 0.1220680
18 12 black walnut 1 27 0.03703704 -3.2958369 0.1220680
19 12 lilac 3 27 0.11111111 -2.1972246 0.2441361
20 12 missing 2 27 0.07407407 -2.6026897 0.1927918



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