R：如何將噪聲簇添加到DBSCAN圖中

Question

我試圖繪製DBSCAN結果。這是我迄今爲止所做的。我的距離矩陣是here。

dbs55_CR_EUCL = dbscan(writeCRToMatrix,eps=0.006, MinPts = 4, method = "dist") 

plot(writeCRToMatrix[dbs55_CR_EUCL$cluster>0,], 
    col=dbs55_CR_EUCL$cluster[dbs55_CR_EUCL$cluster>0], 
    main="DBSCAN Clustering K = 4 \n (EPS=0.006, MinPts=4) without noise", 
    pch = 20) 

這是劇情：

，當我試圖繪製所有羣集包括噪聲集羣，我只能看到我的積2分。

我在尋找什麼是

1. 噪聲集羣的情節，但用不同的符號加分。類似於以下圖像的東西

燈罩簇區域如在下面的圖片

Answer 1

噪聲集羣的ID爲0.R圖通常忽略0的顏色，因此如果要顯示噪點（如黑色）那麼你需要做到以下幾點：

plot(writeCRToMatrix, 
    col=dbs55_CR_EUCL$cluster+1L, 
    main="DBSCAN Clustering K = 4 \n (EPS=0.006, MinPts=4) with noise", 
    pch = 20) 

如果你想爲噪聲不同的符號，那麼你可以做以下（改編自手冊頁）：

library(dbscan) 
n <- 100 
x <- cbind(
    x = runif(10, 0, 10) + rnorm(n, sd = 0.2), 
    y = runif(10, 0, 10) + rnorm(n, sd = 0.2) 
) 

res <- dbscan::dbscan(x, eps = .2, minPts = 4) 
plot(x, col=res$cluster, pch = 20) 
points(x[res$cluster == 0L], col = "grey", pch = "+") 

這裏是代碼，將創建每個簇的陰影凸包

library(ggplot2) 
library(data.table) 
library(dbscan) 


dt <- data.table(x, level=as.factor(res$cluster), key = "level") 
hulls <- dt[, .SD[chull(x, y)], by = level] 

### get rid of hull for noise 
hulls <- hulls[level != "0",] 

cols <- c("0" = "grey", "1" = "red", "2" = "blue") 

ggplot(dt, aes(x=x, y=y, color=level)) + 
    geom_point() + 
    geom_polygon(data = hulls, aes(fill = level, group = level), 
    alpha = 0.2, color = NA) + 
    scale_color_manual(values = cols) + 
    scale_fill_manual(values = cols) 

希望這會有所幫助。