带有颜色和图例的简单ggplot2情况

Question

试图用ggplot2绘制一些图，但无法理解AES中定义的颜色是如何工作的。与审美长度的错误作斗争。

我尝试在主ggplot调用aes中定义颜色来给出传说，但也在geom_line aes中定义颜色。

# Define dataset:
number<-rnorm(8,mean=10,sd=3)
species<-rep(c("rose","daisy","sunflower","iris"),2)
year<-c("1995","1995","1995","1995","1996","1996","1996","1996")

d.flowers<-cbind(number,species,year)
d.flowers<-as.data.frame(d.flowers)

#Plot with no colours:
ggplot(data=d.flowers,aes(x=year,y=number))+
  geom_line(group=species)             # Works fine

#Adding colour:
#Defining aes in main ggplot call:
ggplot(data=d.flowers,aes(x=year,y=number,colour=factor(species)))+
  geom_line(group=species)      
# Doesn't work with data size 8, asks for  data of size 4

ggplot(data=d.flowers,aes(x=year,y=number,colour=unique(species)))+
  geom_line(group=species)         
# doesn't work with data size 4, now asking for data size 8

我怎么能想得更清楚呢？

Answer 1

以下是@Kath的评论作为解决方案。一开始学习起来很微妙，但在aes（）内部或外部的内容才是关键。这里有更多的信息-什么时候审美进入aes（）内部或外部？和许多好的可谷歌的“ggplot美学”为中心的页面，有许多例子可以剪切、粘贴和尝试。

library(ggplot2)
number <- rnorm(8,mean=10,sd=3)
species <- rep(c("rose","daisy","sunflower","iris"),2)
year <- c("1995","1995","1995","1995","1996","1996","1996","1996")
d.flowers <- data.frame(number,species,year, param1, param2)
head(d.flowers)

 #number   species year 
 #1 8.957372      rose 1995     
 #2 7.145144     daisy 1995     
 #3 9.864917 sunflower 1995      
 #4 7.645287      iris 1995     
 #5 4.996174      rose 1996      
 #6 8.859320     daisy 1996     

 ggplot(data = d.flowers, aes(x = year,y = number,
                          group = species, 
                         colour = species)) + geom_line()  

 #note geom_point() doesn't need to be grouped - try:
  ggplot(data = d.flowers, aes(x = year,y = number, colour = species)) + geom_point()