# -----------------------------------------------------------------------------
# calculation of the predicted area depending on the model.
# output to be passed to plotIndiv
# -----------------------------------------------------------------------------
# object: plsda or splsda object
# comp.predicted: prediction based on either component 1 or component 1:2
# dist: distance used in the predict function
# xlim: limit on the x-axis of the simulated variates
# ylim: limit on the y-axis of the simulated variates
# resolution: a total of resolution*resolution variates are simulated
# can only do a 2D prediction: cannot project 3D surface on 2D because we can
# have multiple prediction for same point
# ex: variateXi_1 = variateXj_1 and variateXi_3 = variateXj_3 but
# variateXi_2 !=variate Xj_3
# projection on comp1 and comp3 gives the same point,
# but depending on variate_2, the prediction can be different
#' Calculate prediction areas
#'
#' Calculate prediction areas that can be used in plotIndiv to shade the
#' background.
#'
#' \code{background.predict} simulates \code{resolution*resolution} points
#' within the rectangle defined by xlim on the x-axis and ylim on the y-axis,
#' and then predicts the class of each point (defined by two coordinates). The
#' algorithm estimates the predicted area for each class, defined as the 2D
#' surface where all points are predicted to be of the same class. A polygon is
#' returned and should be passed to \code{\link{plotIndiv}} for plotting the
#' actual background.
#'
#' Note that by default xlim and ylim will create a rectangle of simulated data
#' that will cover the plotted area of \code{plotIndiv}. However, if you use
#' \code{plotIndiv} with \code{ellipse=TRUE} or if you set \code{xlim} and
#' \code{ylim}, then you will need to adapt \code{xlim} and \code{ylim} in
#' \code{background.predict}.
#'
#' Also note that the white frontier that defines the predicted areas when
#' plotting with \code{plotIndiv} can be reduced by increasing
#' \code{resolution}.
#'
#' More details about the prediction distances in \code{?predict} and the
#' supplemental material of the mixOmics article (Rohart et al. 2017).
#'
#' @param object A list of data sets (called 'blocks') measured on the same
#' samples. Data in the list should be arranged in matrices, samples x
#' variables, with samples order matching in all data sets.
#' @param comp.predicted Matrix response for a multivariate regression
#' framework. Data should be continuous variables (see block.splsda for
#' supervised classification and factor reponse)
#' @param dist distance to use to predict the class of new data, should be a
#' subset of \code{"centroids.dist"}, \code{"mahalanobis.dist"} or
#' \code{"max.dist"} (see \code{\link{predict}}).
#' @param xlim,ylim numeric list of vectors of length 2, giving the x and y
#' coordinates ranges for the simulated data. By default will be \eqn{1.2*} the
#' range of object$variates$X[,i]
#' @param resolution A total of \code{resolution*resolution} data are simulated
#' between xlim[1], xlim[2], ylim[1] and ylim[2].
#' @return \code{background.predict} returns a list of coordinates to be used
#' with \code{\link{polygon}} to draw the predicted area for each class.
#' @author Florian Rohart, Al J Abadi
#' @seealso \code{\link{plotIndiv}}, \code{\link{predict}},
#' \code{\link{polygon}}.
#' @references Rohart F, Gautier B, Singh A, LĂȘ Cao K-A. mixOmics: an R package
#' for 'omics feature selection and multiple data integration. PLoS Comput Biol
#' 13(11): e1005752
#' @example ./examples/background.predict-examples.R
#' @export
background.predict <-
function(object, comp.predicted = 1, dist = "max.dist",
xlim = NULL, ylim = NULL, resolution = 100)
{
if (!any(class(object) %in% c("mixo_plsda", "mixo_splsda")))
stop("'background.predict' can only be calculated for 'plsda'
and 'splsda' objects")
if (!any(dist %in% c("max.dist", "centroids.dist", "mahalanobis.dist")))
stop(
"Choose one of the three following distances: 'max.dist',
'centroids.dist' or 'mahalanobis.dist'"
)
if (!comp.predicted %in% c(1, 2))
stop("Can only show predicted background for 1 or 2 components")
if (!is.null(xlim) && length(xlim) != 2)
stop(
"'xlim' must be a vector of two values, indicating the min
and max of the simulated data on variates 1 (x-axis)"
)
if (!is.null(ylim) && length(ylim) != 2)
stop(
"'ylim' must be a vector of two values, indicating the min
and max of the simulated data on variates 2 (y-axis)"
)
if (resolution <= 0)
stop("'resolution' must be a positive value")
# ... = arg to pass to plotIndiv
#plotIndiv(object, style = "graphics", ...)
#plot(-10:10,-10:10,type="n")
####################################
# ---- simulating new data
####################################
X = object$X
Y = object$Y
# we only need to simulate variates
lim = apply(object$variates$X, 2, range) * 1.2
if (is.null(xlim))
xlim = lim[, 1]
if (is.null(ylim))
ylim = lim[, 2]
lim = cbind(xlim, ylim)
increment = apply(lim, 2, function(x) {
sum(abs(x)) / resolution
})
incrementx = increment[1]
incrementy = increment[2]#(abs(ylim[1]) + abs(ylim[2]))/resolution
#incrementy = (abs(zlim[1]) + abs(zlim[2]))/resolution
list.grid = lapply(1:2, function(x) {
seq(lim[1, x], lim[2, x], increment[x])
})
grid = as.matrix(expand.grid(list.grid))
t.pred = list(grid)
ncomp = comp.predicted
J = 1
q = nlevels(Y)
variatesX = list(object$variates$X)
Y.prim = unmap(Y)
####################################
# ---- estimate polygon
####################################
poly.save = vector("list", length = nlevels(Y))
G = cls = list()
if (dist == "max.dist")
{
variatesX = list(X = object$variates [-2][[1]][, 1:comp.predicted,
drop = FALSE])
Y = object$ind.mat
means.Y = matrix(
attr(Y, "scaled:center"),
nrow = nrow(t.pred[[1]]),
ncol = q,
byrow = TRUE
)
sigma.Y = matrix(
attr(Y, "scaled:scale"),
nrow = nrow(t.pred[[1]]),
ncol = q,
byrow = TRUE
)
Cmat = crossprod(Y, variatesX[[1]])
Y = object$Y
#print(variatesX)
Y.hat.temp = Y.hat = list()
for (j in 1:ncomp)
{
A = matrix(
apply(variatesX[[1]][, 1:j, drop = FALSE], 2,
function(y) {
(norm(y, type = "2")) ^ 2
}),
nrow = nrow(t.pred[[1]]),
ncol = j,
byrow = TRUE
)
Y.hat.temp[[j]] = ((as.matrix(t.pred[[1]][, 1:j, drop = FALSE]) /
A) %*%
t(Cmat)[1:j, , drop = FALSE])
# *sigma.Y+means.Y
}
Ypred = sapply(Y.hat.temp, function(x) {
x * sigma.Y + means.Y
},
simplify = "array")
Y.hat[[1]] = Ypred
cls$max.dist = lapply(1:J, function(x) {
matrix(sapply(1:ncomp[x],
# List level
function(y) {
apply(Y.hat[[x]][, , y, drop = FALSE], 1,
# component level
function(z) {
paste(levels(Y)[which(z == max(z))], collapse = "/")
}) # matrix level
}),
nrow = nrow(t.pred[[x]]),
ncol = ncomp[x])
})
cls$max.dist = lapply(1:J, function(x) {
colnames(cls$max.dist[[x]]) =
paste0(rep("comp", ncomp[x]), 1:ncomp[[x]])
rownames(cls$max.dist[[x]]) = rownames(t.pred[[x]])
return(cls$max.dist[[x]])
})
names(cls$max.dist) = names(X)
}
if (dist == "mahalanobis.dist" | dist == "centroids.dist")
{
for (i in 1:J)
{
G[[i]] = sapply(1:q, function(x) {
apply(as.matrix(variatesX[[i]][Y.prim[, x] == 1, 1:ncomp[i] ,
drop = FALSE]), 2, mean)
})
if (ncomp[i] == 1)
G[[i]] = t(t(G[[i]]))
else
G[[i]] = t(G[[i]])
colnames(G[[i]]) = paste0("dim", c(1:ncomp[i]))
rownames(G[[i]]) = levels(Y)
}
names(G) = names(X)
# predicting class of simulated data
if (dist == "centroids.dist")
{
###Start: Centroids distance
cl = list()
centroids.fun = function(x, G, h, i) {
q = nrow(G[[i]])
x = matrix(x,
nrow = q,
ncol = h,
byrow = TRUE)
if (h > 1) {
d = apply((x - G[[i]][, 1:h]) ^ 2, 1, sum)
}
else {
d = (x - G[[i]][, 1]) ^ 2
}
cl.id = paste(levels(Y)[which(d == min(d))], collapse = "/")
}
for (i in 1:J)
{
cl[[i]] = matrix(nrow = nrow(t.pred[[i]]), ncol = ncomp[i])
for (h in 1:ncomp[[i]])
{
cl.id = apply(matrix(t.pred[[i]][, 1:h], ncol = h), 1,
function(x) {
centroids.fun(
x = x,
G = G,
h = h,
i = i
)
})
cl[[i]][, h] = cl.id
}
}
cls$centroids.dist = lapply(1:J, function(x) {
colnames(cl[[x]]) =
paste0(rep("comp", ncomp[x]), 1:ncomp[[x]])
return(cl[[x]])
})
} else if (dist == "mahalanobis.dist") {
### Start: Mahalanobis distance
cl = list()
Sr.fun = function(x, G, Yprim, h, i) {
q = nrow(G[[i]])
Xe = Yprim %*% G[[i]][, 1:h]
#Xr = object$variates$X[, 1:h] - Xe
Xr = variatesX[[i]][, 1:h] - Xe
Sr = t(Xr) %*% Xr / nrow(Yprim)
Sr.inv = solve(Sr)
x = matrix(x,
nrow = q,
ncol = h,
byrow = TRUE)
if (h > 1) {
mat = (x - G[[i]][, 1:h]) %*% Sr.inv %*% t(x - G[[i]][, 1:h])
d = apply(mat ^ 2, 1, sum)
} else {
d = drop(Sr.inv) * (x - G[[i]][, 1]) ^ 2
}
cl.id = paste(levels(Y)[which(d == min(d))], collapse = "/")
}
for (i in 1:J) {
cl[[i]] = matrix(nrow = nrow(t.pred[[1]]), ncol = ncomp[i])
for (h in 1:ncomp[[i]]) {
cl.id = apply(
matrix(t.pred[[i]][, 1:h], ncol = h),
1,
Sr.fun,
G = G,
Yprim = Y.prim,
h = h,
i = i
)
cl[[i]][, h] = cl.id
}
}
cls$mahalanobis.dist = lapply(1:J, function(x) {
colnames(cl[[x]]) =
paste0(rep("comp", ncomp[x]), 1:ncomp[[x]])
return(cl[[x]])
})
}
}
for (ind.area in 1:nlevels(Y))
{
ind1 = which(cls[[dist]][[1]][, comp.predicted] == levels(Y)[ind.area])
if (length(ind1) > 0)
{
# if less than 8 direct neighbours, we keep the point => contour
# from one point from the contour, we can only test the direct
# neighbours to speed up
area = t.pred[[1]][ind1, 1:2, drop = FALSE]#can only do it in 2d
contour = NULL
for (i in 1:nrow(area))
{
areax = area[, 1]#as.numeric(as.character(area[,1]))
areay = area[, 2]#as.numeric(as.character(area[,2]))
a = areax[i]
b = areay[i]
res = 0
for (x in c(a - incrementx, a, a + incrementx))
{
for (y in c(b - incrementy, b, b + incrementy))
{
temp = intersect(which(areax ==
as.numeric(as.character(
x
))),
which(areay ==
as.numeric(as.character(
y
))))
if (length(temp) > 0)
res = res + 1
}
}
if (res != 9)
contour = c(contour, i)
if (length(contour) == 2)
break
}
# now that we have two point of the contour,
# we look for others in the direct neighbours.
added = TRUE
while (added)
{
# as long as we're adding a point in contour,
# we keep looking for another one
added = FALSE
i = length(contour)
point = contour[i]
areax = area[, 1]#round(as.numeric(as.character(area[,1])),7)
areay = area[, 2]#round(as.numeric(as.character(area[,2])),7)
a = areax[point]#round(areax[point],7)
b = areay[point]#round(areay[point],7)
# we want to add the point (x,y) that has the lowest number of
# neighbour (the more extreme on the edge)
neighbour = contour.temp = NULL
# around the point that is in the contour
for (x in c(a - incrementx, a, a + incrementx))
{
# around the point that is in the contour
for (y in c(b - incrementy, b, b + incrementy))
{
# (x,y) is a neighbour of (a,b) and I want to see
# whether it has 8+1 neighbours or less
res = 0
for (xx in c(x - incrementx, x, x + incrementx))
{
for (yy in c(y - incrementy, y, y + incrementy))
{
# (xx,yy) is a neighbour of (x,y)
temp = intersect(which(abs(areax - xx) < 1e-5),
which(abs(areay - yy) < 1e-5))
#which(area[,1]==as.numeric(x) & area[,2]==as.numeric(y))
#print(xx)
#print(yy)
#print(temp)
if (length(temp) > 0)
res = res + 1
}
}
#print(res)
if (res != 9)
# if (x,y) has less than 8+1 neighbour,
# then it's on the edge and I want it,
# only if it's not already in contour
{
# recover which indice in area the point is
ind = intersect(which(abs(areax - x) < 1e-5),
which(abs(areay - y) < 1e-5))
# check whether it is already in contour
if (length(ind) > 0 &&
sum(contour == ind) == 0)
{
contour.temp = c(contour.temp, ind)
neighbour = c(neighbour, res)
#contour = c(contour, ind)
added = TRUE
}
}
}
}
if (length(contour.temp) > 0)
{
contour = c(contour, contour.temp[which.min(neighbour)])
} else {
added = FALSE
}
}
poly = area[contour, ]
poly.save[[ind.area]] = poly
}
}
names(poly.save) = levels(Y)#adjustcolor(color.mixo(ind.area), alpha.f=0.1)
class(poly.save) = "background.predict"
return(poly.save)
}
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