Hello,
I am using e1071 to run support vector machine. I would like to plot
the data with lattice and specifically show the hyperplanes created by
the system.
I can store the hyperplane as a contour in an object, and I can plot
one object at a time. Since there will be thousands of elements to
plot, I can't manually add them one by one to the plot, so I tried to
loop into them, but only the last is added.
Here it the working example for more clarity:
```
library(e1071)
library(lattice)
library(latticeExtra)
make.grid <- function(x, n = 1000) {
grange = apply(x, 2, range)
x1 = seq(from = grange[1,1], to = grange[2,1], length = n)
x2 = seq(from = grange[1,2], to = grange[2,2], length = n)
expand.grid(X1 = x1, X2 = x2)
}
plot_list <- list()
for (i in 1:10) {
x1 = rnorm(100, mean = 0.2, sd = 0.15)
y1 = rnorm(100, mean = 0.7, sd = 0.15)
y2 = rnorm(100, mean = 0.2, sd = 0.15)
x2 = rnorm(100, mean = 0.75, sd = 0.15)
df = data.frame(x = c(x1,x2), y=c(y1,y2),
z=c(rep(0, length(x1)), rep(1, length(x2))))
df$z = factor(c(rep(0, length(x1)), rep(1, length(x2))))
df[, "train"] <- ifelse(runif(nrow(df)) < 0.8, 1, 0)
trainset <- df[df$train == 1, ]
testset <- df[df$train == 0, ]
trainColNum <- grep("train", names(df))
trainset <- trainset[, -trainColNum]
testset <- testset[, -trainColNum]
svm_model <- svm(z ~ .,
data = trainset,
type = "C-classification",
kernel = "linear",
scale = FALSE)
# generate contour
xmat = make.grid(matrix(c(testset$x, testset$y),
ncol = 2, byrow=FALSE))
xgrid = as.data.frame(xmat)
names(xgrid) = c("x", "y")
z = predict(svm_model, xgrid)
xyz_dat = as.data.frame(cbind(xgrid, z))
plot_list[[i]] = contourplot(z ~ y+x, data=xyz_dat, pretty = TRUE,
xlim=c(-1,50), ylim=c(-0.001, 0.05),
labels = FALSE, col = "blue", lwd = 0.5)
}
# the contour is stored in the object plot_list
str(plot_list) # confirm that there is data here
# I can add one element at the time to lattice's xyplot and store it
in an object P
P = xyplot(y ~ x, group = z, data = df,
pch = 16, cex = 1.5, alpha = 0.25) + as.layer(plot_list[[1]]) +
as.layer(plot_list[[2]])
plot(P) # this demonstrates that the lines are not the same
# but if I add the elements via loop, it does not work
for (i in 1:length(plot_list)) {
print(i)
P = xyplot(y ~ x, group = z, data = df,
pch = 16, cex = 1.5, alpha = 0.25) + as.layer(plot_list[[i]])
}
plot(P)
```
Am I missing something?
Thank you