r - 提高 ggplot2 r 中 geom_text 条目的分辨率

Question

关于如何提高 geom_text 的分辨率以使分辨率与轴标签的分辨率相当的任何建议？谢谢

df <- data.frame("x" = c(1,2,3,4),"y" = c(15,19,35,47))

p<-ggplot(df,aes(x,y))
p<- p + geom_point(size=1)

p<- p + geom_smooth(method="lm", se=FALSE, formula=y~x)
p<- p + xlab("Better Resolution")
p<- p +ylab("Better Resolution")

p<- p +opts(axis.title.x = theme_text(family="Times",face="bold", size=25, colour = "Black",vjust=0)) 

p<- p +opts(axis.title.y = theme_text(family="Times",face="bold", size=25, angle =90, colour ="Black",vjust=0.4))

p<- p + geom_text(aes(x = 3.5, y = 37, label ="123456789"),size=12, parse = TRUE)
p

#The zoomed in text looks like this after saving using ggsave

#Information about my version of R and OS

sessionInfo()
R version 2.15.1 (2012-06-22)
Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

R.version
           _                            
platform       x86_64-apple-darwin9.8.0     
arch           x86_64                       
os             darwin9.8.0                  
system         x86_64, darwin9.8.0          
status                                      
major          2                            
minor          15.1                         
year           2012                         
month          06                           
day            22                           
svn rev        59600                        
language       R                            
version.string R version 2.15.1 (2012-06-22)
nickname       Roasted Marshmallows  

##############
#The actual code I am using looks like this:

#function that creates the line equation
lm_eqn = function(df){
m = lm(y ~ x, df)
eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(r)^2~"="~r2,
list(a = format(coef(m)[1], digits = 2),
b = format(coef(m)[2], digits = 2),
r2 = format(summary(m)$r.squared, digits = 3)))
as.character(as.expression(eq))
}


#creates basic plot and adds a line
p<-ggplot(df, aes(x,y))
p<- p + geom_point(alpha=1/10, colour="blue", size=5)

#controls background colours
p<-p + theme_bw()

#adds the labels, titles and makes them pretty

p<- p + geom_smooth(method="lm", se=FALSE, formula=y~x,colour="black")
p<- p + xlab("Species similarity for site pair (Tsim variable 'a')")
p<- p +ylab("Trait similarity for site pairs (Tsim)")
p<- p +opts(title="Species vs. Trait combination similarity 2-5m")
p<- p +opts(plot.title = theme_text(family="Times",face="bold", size=18, colour =   "Black",vjust=1)) 
p<- p +opts(axis.title.x = theme_text(family="Times",face="bold", size=15, colour = "Black",vjust=0)) 
p<- p +opts(axis.title.y = theme_text(family="Times",face="bold", size=15, angle =90, colour =  "Black",vjust=0.4))

#adds the equation
p<- p + geom_text(aes(x = 0.015, y = 0.08, label = lm_eqn(df)),size=6,  family="Times",face="italic", parse = TRUE)

ggsave(p,file="tsim.a.0-2.pdf") 

Answer 1

为什么不使用ggsave. 您在屏幕上看到的不一定是使用 pdf 或 ps 设备在输出图形中呈现的内容。在使用 ggplot 0.9.1 的 Windows 7 上使用 R2.15.1 的未编辑代码时，我没有看到任何问题。

ggsave我使用并放大保存了您的屏幕图，并且 pdf 看起来很棒：

使用ggsave("plot.pdf")（您可以设置其他几个可选参数，包括另存为 eps）。这会将最后一个图（默认情况下）保存到当前工作目录。检查情节。如果文字看起来仍然很有趣，我建议您的 Times 字体安装可能有问题。

在这种情况下，您应该尝试省略字体规范，以便 R 选择它的默认字体系列。

您还应该切换到theme代替opts和element_text代替theme_text（目前！）。

**编辑**

好的，我想我在这里找到了解决您问题的方法，这要归功于kohske和mbask。显然，通过为您的标签创建一个数据框并将其传递给 geom_text 可以实现更好的结果。

尝试使用：

df <- data.frame("x" = c(1,2,3,4),"y" = c(15,19,35,47))

lm_eqn = function(df){
m = lm(y ~ x, df)
eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(r)^2~"="~r2,
list(a = format(coef(m)[1], digits = 2),
b = format(coef(m)[2], digits = 2),
r2 = format(summary(m)$r.squared, digits = 3)))
as.character(as.expression(eq))
}

### NEW ###
# Create a data frame to hold your label variables
data.label <- data.frame(
x = 0.015,
y = 0.08,
label = c(lm_eqn(df))
)

#creates basic plot and adds a line
p<-ggplot(df, aes(x,y))
p<- p + geom_point(alpha=1/10, colour="blue", size=5)

#controls background colours
p<-p + theme_bw()

#adds the labels, titles and makes them pretty

p<- p + geom_smooth(method="lm", se=FALSE, formula=y~x,colour="black")
p<- p + xlab("Species similarity for site pair (Tsim variable 'a')")
p<- p +ylab("Trait similarity for site pairs (Tsim)")
p<- p +opts(title="Species vs. Trait combination similarity 2-5m")
p<- p +opts(plot.title = theme_text(family="Times",face="bold", size=18, colour =   "Black",vjust=1)) 
p<- p +opts(axis.title.x = theme_text(family="Times",face="bold", size=15, colour = "Black",vjust=0)) 
p<- p +opts(axis.title.y = theme_text(family="Times",face="bold", size=15, angle =90, colour =  "Black",vjust=0.4))

### NEW
####   Change your call to geom_text ####
p<- p + geom_text(data = data.label, aes(x = x , y = y , label = label ) , size=6,  family="Times" , face="italic" , parse = TRUE)

ggsave(p,file="tsim.a.0-2.pdf") 

我在 Mac OS X 10.7.4 和 R 2.15.1 上得到了这个：

Answer 2

使用annotate()而不是geom_text()用于图形上的单个注释。否则，ggplot()将尝试为每个数据点绘制相同的文本，从而导致奇怪的分辨率。