在R中訪問坐標heatmap.2

Question

我已經用heatmap.2繪制了兩個在[0,1]上定義的變量的圖。 我現在想畫一個abline(v=0.2) 。 這將被“放錯位置”（相對於我想要的，不是我想要的R的內部logid），因為heatmap.2還會在繪圖區域中放置其他內容，例如顏色鍵（和heatmap.2的軸是，我猜是，內部也有其他事情，因為在下面的示例中我只是重命名了軸）。

我的問題是：我怎樣才能最方便地放置像是abline類的東西，最好是根據實際熱圖的坐標而不是整個繪圖區域。

rm(list=ls())
library(rpart)
library(gplots)
library(RColorBrewer)

N <- 150

# just some data
X1 <- runif(N)
X2 <- runif(N)
y <- as.factor((X1<.2+rnorm(N,sd=0.2))|(X2>.7+rnorm(N,sd=0.1)))   

theData <- data.frame(y,X1,X2)

X1grid <- seq(0,1,by=.02)
X2grid <- seq(0,1,by=.02)
newData <- expand.grid(X2=X2grid,X1=X1grid)

FitSingle <- rpart(y~.,data=theData)
PredictionsSingle <- matrix(as.logical(predict(FitSingle, newdata=newData, type="class"))+0,nrow=length(X2grid))

names <- rep("", length(X2grid)) 
names[seq(1,length(X2grid), length(X2grid)/10)] <- seq(0, .9, by=.1) # not fully checked, but should be OK
rownames(PredictionsSingle) <- names
colnames(PredictionsSingle) <- names

rc <- colorRampPalette(c("darkgreen", "white", "purple3"))(n = nrow(X2grid))
heatmapplotSingle <- heatmap.2(PredictionsSingle, Rowv=NA, Colv=NA, col=rc,density.info="none",trace="none",revC=T)
abline(v=0.2) # should be at 0.2, not at roughly .6. should also stay in the heatmap

Answer 1

如評論中所述，add.expr是解決方法：

heatmapplotSingle <- heatmap.2(PredictionsSingle, Rowv = NA, Colv = NA, col = rc, 
                           density.info = "none", trace = "none", revC = T,
                           main = "Classification Tree full sample", 
                           add.expr  = { segments(0.2*ncol(MeanPrediction), 0, 0.2*ncol(MeanPrediction),
                                                  .7*nrow(MeanPrediction), lwd = 3, col="darkslateblue");
                                         segments(0.2*ncol(MeanPrediction), .7*nrow(MeanPrediction), 1*ncol(MeanPrediction), 
                                                  .7*nrow(MeanPrediction), lwd = 3, col = "darkslateblue")}
                           , srtCol = 0)