爲geom_text圖層顯示單獨的圖例？

Question

我有以下情節：

library(ggplot2) 

ib<- data.frame(
    category = factor(c("Cat1","Cat2","Cat1", "Cat1", "Cat2","Cat1","Cat1", "Cat2","Cat2")), 
    city =  c("CITY1","CITY1","CITY2","CITY3", "CITY3","CITY4","CITY5", "CITY6","CITY7"), 
    median =  c(1.3560, 2.4830, 0.7230, 0.8100, 3.1480, 1.9640, 0.6185, 1.2205, 2.4000), 
    samplesize = c(851, 1794, 47, 189, 185, 9, 94, 16, 65) 
) 


p<-ggplot(data=ib, aes(x=city, y=category, size=median, colour=category, label=samplesize)) + 
    geom_point(alpha=.6) + 
    scale_area(range=c(1,15)) + 
    scale_colour_hue(guide="none") + 
    geom_text(aes(size = 1), colour="black") 
p 

（我繪製的圓圈比例的中位值和文本標籤覆蓋佔樣本量爲http://imgur.com/T82cF圖像）

有什麼辦法分離這兩個傳說？我希望有一個傳說（標記爲「中位數」）給出圓圈的比例，另一個傳說用單個字母「a」（或者更好的數字）來標註「樣本量」。由於這兩個屬性沒有任何關係，因此將它們捆綁在同一個圖例中是沒有意義的。

我已經試過各種組合，但最好我能想出是完全失去了文字提示:)

感謝您的回答！

Answer 1

更新scale_area已棄用;改用scale_size。 gtable函數gtable_filter()用於提取圖例。修改後的代碼用於替換其中一個圖例中的默認圖例關鍵字。

如果你仍然在尋找你的問題的答案，這裏似乎是你想要的大部分，儘管這是一個地方的黑客。圖例中的符號可以使用kohske's comment here

難度試圖應用兩種不同大小的映射。所以，我在美學聲明中留下了點尺寸映射，但是從美學聲明中刪除了標籤尺寸映射。這意味着標籤大小必須根據samplesize（fsamplesize）的因子版本的離散值進行設置。得到的圖表幾乎是正確的，但標籤大小的圖例（即樣本大小）未繪製。爲了解決這個問題，我繪製了一個圖表，其中包含根據樣本大小因子版本（但忽略點大小映射）的標籤大小映射，以便提取其圖例，然後可以將其插入到第一個圖表中。

## Your data 
ib<- data.frame(
    category = factor(c("Cat1","Cat2","Cat1", "Cat1", "Cat2","Cat1","Cat1", "Cat2","Cat2")), 
    city =  c("CITY1","CITY1","CITY2","CITY3", "CITY3","CITY4","CITY5", "CITY6","CITY7"), 
    median =  c(1.3560, 2.4830, 0.7230, 0.8100, 3.1480, 1.9640, 0.6185, 1.2205, 2.4000), 
    samplesize = c(851, 1794, 47, 189, 185, 9, 94, 16, 65) 
) 

## Load packages 
library(ggplot2) 
library(gridExtra) 
library(gtable) 
library(grid) 

## Obtain the factor version of samplesize. 
ib$fsamplesize = cut(ib$samplesize, breaks = c(0, 100, 1000, Inf)) 

## Obtain plot with dot size mapped to median, the label inside the dot set 
## to samplesize, and the size of the label set to the discrete levels of the factor 
## version of samplesize. Here, I've selected three sizes for the labels (3, 6 and 10) 
## corresponding to samplesizes of 0-100, 100-1000, >1000. The sizes of the labels are 
## set using three call to geom_text - one for each size. 

p <- ggplot(data=ib, aes(x=city, y=category)) + 
    geom_point(aes(size = median, colour = category), alpha = .6) + 
    scale_size("Median", range=c(0, 15)) + 
    scale_colour_hue(guide = "none") + theme_bw() 

p1 <- p + 
    geom_text(aes(label = ifelse(samplesize > 1000, samplesize, "")), 
     size = 10, color = "black", alpha = 0.6) + 
    geom_text(aes(label = ifelse(samplesize < 100, samplesize, "")), 
     size = 3, color = "black", alpha = 0.6) + 
    geom_text(aes(label = ifelse(samplesize > 100 & samplesize < 1000, samplesize, "")), 
     size = 6, color = "black", alpha = 0.6) 


## Extracxt the legend from p1 using functions from the gridExtra package 
g1 = ggplotGrob(p1) 
leg1 = gtable_filter(g1, "guide-box") 


## Keep p1 but dump its legend 
p1 = p1 + theme(legend.position = "none") 


## Get second legend - size of the label. 
## Draw a dummy plot, using fsamplesize as a size aesthetic. Note that the label sizes are 
## set to 3, 6, and 10, matching the sizes of the labels in p1. 

dummy.plot = ggplot(data = ib, aes(x = city, y = category, label = samplesize)) + 
    geom_point(aes(size = fsamplesize), colour = NA) + 
    geom_text(show.legend = FALSE) + theme_bw() + 
    guides(size = guide_legend(override.aes = list(colour = "black", shape = utf8ToInt("N")))) + 
scale_size_manual("Sample Size", values = c(3, 6, 10), 
    breaks = levels(ib$fsamplesize), labels = c("< 100", "100 - 1000", "> 1000")) 

## Get the legend from dummy.plot using functions from the gridExtra package 
g2 = ggplotGrob(dummy.plot) 
leg2 = gtable_filter(g2, "guide-box") 


## Arrange the three components (p1, leg1, leg2) using functions from the gridExtra package 
## The two legends are arranged using the inner arrangeGrob function. The resulting 
## chart is then arranged with p1 in the outer arrrangeGrob function. 
ib.plot = arrangeGrob(p1, arrangeGrob(leg1, leg2, nrow = 2), ncol = 2, 
     widths = unit(c(9, 2), c("null", "null"))) 

## Draw the graph 
grid.newpage() 
grid.draw(ib.plot) 

Answer 2

這實際上並不直接解決您的問題，但它是我怎麼可能去與一般特性創建圖形你描述：

ib$ss <- paste("n = ",ib$samplesize,sep = "") 

ggplot(data=ib, aes(x=city, y=category, size=median, colour=category, label=ss)) + 
    geom_point(alpha=.6) + 
    geom_text(size = 2, vjust = -1.2,colour="black") + 
    scale_colour_hue(legend = FALSE) 

我刪除了scale_area片，因爲我我不知道它的用途是什麼，它對我造成了錯誤。

所以這裏的基本原理是樣本量信息更像是對我的註釋，而不是一些值得自己的規模和傳說的東西。當然，意見可能會有所不同，但我認爲如果你覺得它有用，我會把它放在那裏。

Answer 3

這也不會回答你的問題。我已經在圈內留下了samplesize。另外，對我而言，samplesize更像是一個註釋而不是傳說。 但我認爲你使用的是舊版本的ggplot2。版本0.9.0在ggplot2中發生了一些變化。我已經做出以下更改。

p<-ggplot(data=ib, aes(x=city, y=category, size=median, colour=category, label=samplesize)) + 
    geom_point(alpha=.6) + 
    scale_area(range = c(1,15)) + # range instead of to 
    scale_colour_hue(guide = "none") + # guide instead of legend 
    geom_text(size = 2.5, colour="black") 
p