在每个测试用例之后清除内存数据库(Clear the in memory database after every testcase)

 我们可以使用dplyr::data_frame构建一个只有你想要的动态绘制的x值的数据帧。 我添加了另一个pdf，以证明您希望它呈现的方式将起作用。 
 
library(dplyr)
# to use data_frame

ggplot() +
  geom_line(data=data_frame(x=seq(2,30, 0.25), y = dnorm(x, mean = 5, sd = 1)),
            aes(x, y),  color = "black") +
  geom_line(data=data_frame(x=seq(40,70, 0.25), y = dnorm(x, mean = 60, sd = 5)),
            aes(x, y),  color = "red") +
  xlim(-5,80)+
  scale_y_continuous(breaks = NULL) 
 
  
 
 更新 
 
 您也可以通过在aes(...)内移动color=来标记它们： 
 
ggplot() +
  geom_line(data=data_frame(x=seq(2,30, 0.25), y = dnorm(x, mean = 5, sd = 1)),
            aes(x, y,  color = "mean:5, sd:1")) +
  geom_line(data=data_frame(x=seq(40,70, 0.25), y = dnorm(x, mean = 60, sd = 5)),
            aes(x, y,  color = "mean:60, sd:5")) +
  xlim(-5,80)+
  scale_y_continuous(breaks = NULL) +
  scale_color_manual(values = c("mean:5, sd:1" = "black",
                                "mean:60, sd:5" = "red"))
 
  
 
 UPDATE2 
 
 你的密度函数适合我。 
 
dTDF<-function(x,g,a,b,k){
  exp(-exp(-(x/a)+((a*k)/(g-x))-b))*(exp(-(x/a)+((a*k)/(g-x))-b))*((1/a)-((a*k)/((g-x)^2)))
  } 

df1 <- data_frame(x=seq(2500,11300, 100), 
                  y = dTDF(x,g=11263,a=1185, b=-4, k=-0.5))
df2 <- data_frame(x=seq(7000,14300, 100), 
                  y = dTDF(x,g=15263,a=1105, b=-10, k=-0.5))


ggplot() + 
  geom_line(data = df1, aes(x, y))+ 
  geom_line(data = df2, aes(x, y)) +
  xlim(1000, 15000)
 
  

We can construct a dataframe with the only the x-values you want plotted on the fly using dplyr::data_frame. I added another p.d.f. to demonstrate that the way you want it presented will work.
 
library(dplyr)
# to use data_frame

ggplot() +
  geom_line(data=data_frame(x=seq(2,30, 0.25), y = dnorm(x, mean = 5, sd = 1)),
            aes(x, y),  color = "black") +
  geom_line(data=data_frame(x=seq(40,70, 0.25), y = dnorm(x, mean = 60, sd = 5)),
            aes(x, y),  color = "red") +
  xlim(-5,80)+
  scale_y_continuous(breaks = NULL) 
 
 
Update
 
You can also label them like so, by moving the color= inside the aes(...):
 
ggplot() +
  geom_line(data=data_frame(x=seq(2,30, 0.25), y = dnorm(x, mean = 5, sd = 1)),
            aes(x, y,  color = "mean:5, sd:1")) +
  geom_line(data=data_frame(x=seq(40,70, 0.25), y = dnorm(x, mean = 60, sd = 5)),
            aes(x, y,  color = "mean:60, sd:5")) +
  xlim(-5,80)+
  scale_y_continuous(breaks = NULL) +
  scale_color_manual(values = c("mean:5, sd:1" = "black",
                                "mean:60, sd:5" = "red"))
 
 
Update2
 
Your density function works for me.
 
dTDF<-function(x,g,a,b,k){
  exp(-exp(-(x/a)+((a*k)/(g-x))-b))*(exp(-(x/a)+((a*k)/(g-x))-b))*((1/a)-((a*k)/((g-x)^2)))
  } 

df1 <- data_frame(x=seq(2500,11300, 100), 
                  y = dTDF(x,g=11263,a=1185, b=-4, k=-0.5))
df2 <- data_frame(x=seq(7000,14300, 100), 
                  y = dTDF(x,g=15263,a=1105, b=-10, k=-0.5))


ggplot() + 
  geom_line(data = df1, aes(x, y))+ 
  geom_line(data = df2, aes(x, y)) +
  xlim(1000, 15000)