[R-sig-Geo] lesions distribution
José Mauricio Cunha Fernandes
mauricio at cnpt.embrapa.br
Fri Oct 20 19:58:36 CEST 2006
Dear Friends,
I am a plant pathologist working in Southern Brazil. I have a research
project dealing with the development of plant disease simulators.
Amongst the research topics under investigation is the distribution
of disease symptoms within a particular leaf. We used a scanner to
acquire images from wheat leaves infected with rust (a wheat disease).A
grid x(-6,6) and y(0,100) was superimposed on each image and the number
of lesions (z) in each cell of the grid was recorded. We have a few
hundreds leaves examined. A example of data is shown bellow (leaf_46.txt).
x y z
0 0 1
2 36 1
1 18 1
1 17 2
1 32 2
1 24 1
1 23 1
0 46 1
1 43 7
1 63 4
-1 61 2
1 55 2
2 57 2
-1 57 2
-1 52 2
-1 51 2
1 51 2
3 52 8
0 37 2
-1 66 6
1 69 2
2 72 4
-4 73 3
-4 72 1
-1 70 2
-4 67 2
2 59 2
-1 78 3
0 77 1
-2 76 2
1 75 3
2 27 1
1 29 1
0 27 1
This R code bellow was used to visualize:
leaf_46 <- read.table("leaf_46.txt",header=T)
win <- list(x=c(-6,-6,0,6,6), y=c(0,80,100,80,0))
plot(win, asp=1, type="n")
polygon(win)
points(leaf_46[,1:2])
I am reading on published literature but I am still a little confused on
choosing an appropriate technique to analyze the data. Therefore, any
suggestions from the list members will be very welcome.
Thanks very much for your attention
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