[R] ggplot2 plot with symbols and then add line

[stephen sefick]

r <-(structure(list(TSS = c(2.8, 8.4, 11, 1.3, 4.2, 2, 3.4, 14, 8.2,
3.1, 1.4, 0.9, 0.5, 6.1, 9.2, 0.6, 1, 11, 2.4, 1.2, 1.3, 1.3,
0, 1.8, 8, 11, 11, 8.5, 8.5, 1.8, 13, 4.4, 1.4, 2.1, 0.5, 25,
25, 9.3, 6.1, 1.6, 1.5, 19, 19, 24, 9.6, 1.8, 1.4, 1), GPP = c(1.213695235,
3.817313822, 1.267930498, 10.45692825, 3.268295623, 3.505286001,
4.468225245, 0.915653726, 1.635617261, 3.726133898, 1.363453706,
13.99650967, 1.581182762, 0.417618143, 0.741080504, 1.366790205,
0.969326797, 0.412440872, 1.780215366, 3.515743675, 8.248491445,
0.125726306, 13.95880794, 4.850627229, -0.438311644, 1.537773727,
1.537773727, 3.249103284, 3.249103284, 2.470317011, 0.768531626,
2.633107621, 3.113199095, 0.773824094, 3.208461305, 0.680150068,
0.680150068, 0.026385752, 0.369310858, 8.049276658, 7.487378383,
0.950072035, 0.950072035, 0.763580377, 0.333244629, 5.475999014,
9.235631398, 2.587682905), RiverMile = c(148L, 179L, 185L, 202L,
179L, 185L, 190L, 119L, 148L, 179L, 185L, 202L, 215L, 119L, 202L,
198L, 215L, 148L, 198L, 190L, 202L, 215L, 198L, 198L, 215L, 148L,
148L, 202L, 202L, 215L, 119L, 179L, 185L, 190L, 198L, 61L, 61L,
119L, 148L, 202L, 202L, 61L, 61L, 119L, 148L, 185L, 202L, 215L
)), .Names = c("TSS", "GPP", "RiverMile"), class = "data.frame",
row.names = c(12L,
13L, 14L, 19L, 25L, 26L, 28L, 34L, 35L, 36L, 37L, 42L, 44L, 58L,
75L, 85L, 88L, 91L, 97L, 107L, 142L, 144L, 155L, 166L, 169L,
185L, 186L, 201L, 202L, 207L, 219L, 221L, 222L, 224L, 226L, 230L,
231L, 250L, 251L, 258L, 283L, 287L, 288L, 303L, 304L, 306L, 311L,
313L)))

library(lattice)
library(ggplot2)
z <- nls(GPP~(a/(TSS+b)), start=c(a=0.01, b=0.01), data=r)
f <- seq(-1, 29, length=100)
y <- coef(z)["a"]/(f+coef(z)["b"])
pred <- data.frame(GPP = f, TSS = y)

#this is what I can do
qplot(TSS, GPP, data=r, colour=as.factor(RiverMile)) +
geom_line(data=pred, colour ="black")

#I would like to do this and then add the nls line
qplot(TSS, GPP, data=r,
shape=as.factor(RiverMile))+scale_shape_manual(values=1:9)

#how do you undo the mapping of shape to add a line is my question
#thanks

-- 
Stephen Sefick
Research Scientist
Southeastern Natural Sciences Academy

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis