分组数据并绘制多条线

Question

我想在R中为这个数据集绘制多条线:(x =年,y =值)

School_ID   Year    Value
A           1998    5
B           1998    10
C           1999    15
A           2000    7
B           2005    15

每所学校都有不同年份的数据.我希望每所学校都有一行.

Answer 1

让我们创建一些数据:

dd = data.frame(School_ID = c("A", "B", "C", "A", "B"),
  Year = c(1998, 1998, 1999, 2000, 2005),
  Value = c(5, 10, 15, 7, 15))

然后在基础图形中创建一个图,我们创建一个组的初始图:

plot(dd$Year[dd$School_ID=="A"], dd$Value[dd$School_ID=="A"], type="b",
     xlim=range(dd$Year), ylim=range(dd$Value))

然后迭代添加行:

lines(dd$Year[dd$School_ID=="B"], dd$Value[dd$School_ID=="B"], col=2, type="b")
lines(dd$Year[dd$School_ID=="C"], dd$Value[dd$School_ID=="C"], col=3, type="b")

我曾经用来type="b"表示点和线.

或者,使用ggplot2:

require(ggplot2)
##The values Year, Value, School_ID are
##inherited by the geoms
ggplot(dd, aes(Year, Value,colour=School_ID)) + 
    geom_line() + 
    geom_point()

Answer 2

这是你想要的吗？您需要group = School_id告诉ggplot2为每所学校绘制单独的行.如果你想横轴,以incluude 1998年至2005年间的所有年份,然后取出factor在x = factor(year)

  library(ggplot2)

df = read.table(text = "School_id Year Value 
 A           1998    5
 B           1998    10
 C           1999    15
 A           2000    7
 B           2005    15", sep = "", header = TRUE)

ggplot(data = df, aes(x = factor(Year), y = Value, color = School_id)) +       
  geom_line(aes(group = School_id)) + geom_point()