我如何突出ggplot上的差异？ [英] How can I highlight variance over a ggplot?

问题描述

我找不到应该如何提出这个问题，所以我使用了这个方法。

I can't find out how should I put up this ques so I used this method.

我有一个纬度 - 经度数据集。这是我的数据集：

I have a latitude-longitude dataset. The image posted below is what I want to produce.. This is my dataset:

Latitude    Longitude
21.06941667 71.07952778
21.06941667 71.07952778
21.06666667 71.08158333
21.07186111 71.08688889
21.08625    71.07083333
21.08719444 71.07286111
21.08580556 71.07686111
21.07894444 71.08225
....

我使用geom_path（）来查找路径。现在，如图所示。我已经突出了我想要做的道路周围的白色变化。
这就是我计算方差的方法：

I have used geom_path() to find the path. Now, As shown in fig. I have highlighted the variance with white color around the path which I want to do. This is how I calculated variance:

var.latitude <- var(Data$Latitude)
var.longitude <- var(Data$Longitude)

我标记了点使用geom_errorbar（）：

I have marked the variance over the points using geom_errorbar():

geom_errorbar(aes(x=Latitude,y=Longitude, ymin=Longitude-var.longitude, ymax=Longitude+var.longitude),width=0.001)+
geom_errorbarh(aes(xmin=Latitude-var.latitude,xmax=Latitude+var.latitude),height=0.001)

任何人都可以告诉我该如何突出显示白色区域？

Can anyone tell me how should I highlight the white area?

推荐答案

我正在用ggplot的多边形功能来解决这个问题，请参阅文档

I'm approaching this with the polygon feature of ggplot, see the documentation

library(ggplot2)    
data = rbind.data.frame(c(21.06941667, 71.07952778),
                        c(21.06666667, 71.08158333 ),
                        c(21.07186111, 71.08688889 ),
                        c(21.08625   , 71.07083333 ),
                        c(21.08719444, 71.07286111 ),
                        c(21.08580556, 71.07686111 ),
                        c(21.07894444, 71.08225 ))
names(data) = c("Latitude",     "Longitude")

您的差异非常小，我乘以10使其在图中可见。请注意，在您的问题图中，您从错误栏的翅片中绘制区域，这几乎肯定不是您想要的。

Your variance is quite small, I multiplied by 10 for it to be visible in the graph. Note that in the graph in your question you draw the area from the fins of the errorbars, which is almost certainly not what you want.

var.latitude <- var(data$Latitude)*10
var.longitude <- var(data$Longitude)*10

将这个区域计算为一个是一项琐碎的任务，以上。我发现最简单的方法是为每个路径重叠两个多边形，并为每个点重叠一个多边形。肯定可能有更优雅的方式，但嘿，它的作品。

Calculating this area as one is a menial task as also noted in the comments above. I found the easiest way to do this is overlapping two polygons for each path plus a polygon for each point. There sure may be more elegant ways, but hey, it works.

pos.poly = data.frame(id = paste0("c", as.character(1)), 
                      x = c(data$Latitude[1]-var.latitude, data$Latitude[1], data$Latitude[1]+var.latitude, data$Latitude[1]), 
                      y = c(data$Longitude[1], data$Longitude[1]+var.longitude, data$Longitude[1], data$Longitude[1]-var.longitude))
for(i in 2:dim(data)[1]){
  loc.pos1 = data.frame(id = paste0("a", as.character(i)), 
                       x = c(data$Latitude[i-1]-var.latitude, data$Latitude[i]-var.latitude, 
                             data$Latitude[i]+var.latitude, data$Latitude[i-1]+var.latitude), 
                       y = c(data$Longitude[i-1], data$Longitude[i], data$Longitude[i], data$Longitude[i-1]))
  pos.poly = rbind(pos.poly, loc.pos1)
  loc.pos2 = data.frame(id = paste0("b", as.character(i)), 
                        x = c(data$Latitude[i-1], data$Latitude[i], data$Latitude[i], data$Latitude[i-1]), 
                        y = c(data$Longitude[i-1]+var.longitude, data$Longitude[i]+var.longitude, 
                              data$Longitude[i]-var.longitude, data$Longitude[i-1]-var.longitude))
  pos.poly = rbind(pos.poly, loc.pos2)
  loc.pos3 = data.frame(id = paste0("c", as.character(i)), 
                        x = c(data$Latitude[i]-var.latitude, data$Latitude[i], data$Latitude[i]+var.latitude, data$Latitude[i]), 
                        y = c(data$Longitude[i], data$Longitude[i]+var.longitude, data$Longitude[i], data$Longitude[i]-var.longitude))
  pos.poly = rbind(pos.poly, loc.pos3)
}

这是从两个数据集我们需要多次指定 data 和 aes 。

This is plotted from two datasets so we need to specify data and the aes a couple more times.

plot1 = ggplot(pos.poly, aes(x=x, y=y)) + geom_polygon(aes(group=id), fill="white") + geom_path(data = data, aes(x=Latitude, y=Longitude))
plot1 = plot1 + xlab("Latitude") + ylab("Longitude") +  
  geom_errorbar(data = data, aes(x=Latitude,y=Longitude, ymin=Longitude-var.longitude, ymax=Longitude+var.longitude)) +
  geom_errorbarh(data = data, aes(xmin=Latitude-var.latitude,xmax=Latitude+var.latitude, x=Latitude, y=Longitude))
print(plot1)

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