4

我有 6 个线性约束。我知道如何手动和通过r. 我正在寻找一种简单的方法来获得可行区域的插图。

我试图ggplot2这样做没有任何成功。

以下是约束：x1 >= 0, x2 >= 0, x2 <= 10和x2 <= 12 - 2/5 * x1, x2 <= 18 - x1,x2 <= 18 - x1

require(ggplot2)

# x2 <= 12 - 2/5*x1
fun1 = function(x1){
     x2 = 12 - 2/5*x1
     return(x2)
}

# x2 <= 18 - x1
fun2 = function(x1){
    x2 = 18 - x1
    return(x2)
}

# x2 = 44 - 3*x1
fun3 = function(x1){
    x2 = 44 - 3*x1
    return(x2)
}

x1 = seq(0,20)
mydf = data.frame(x1, fun1(x1), fun2(x1),fun3(x1),rep(10,length(x1)))
names(mydf) = c('x1','y1','y2','y3','y4')
mydf$y5 = rep(0,length(x1))

p0 = ggplot(mydf, aes(x = x1)) + 
     coord_cartesian(ylim=c(0,10),xlim = c(0,20))+                      
     geom_line(aes(y = y1), colour = 'blue') +
     geom_line(aes(y = y2), colour = 'green') +
     geom_line(aes(y = y3), colour = 'red') +
     geom_line(aes(y = y4), colour = 'purple') +
     geom_line(aes(y = y5), colour = 'black')

p0 +  geom_area(aes(y = pmin(y1,y2,y3,y4,y5)), fill = 'gray60')

谢谢你的帮助！

编辑y5：从pmin函数中删除最后一个技巧：

 p0 +  geom_area(aes(y = pmin(y1,y2,y3,y4,y5)), fill = 'gray60')
4

1 回答 1

0

我的问题出在最后一个变量y5中。pmin从函数中删除它就可以了。

p0 = ggplot(mydf, aes(x = x1)) + 
    coord_cartesian(ylim=c(0,10),xlim = c(0,20))+                      
    geom_line(aes(y = y1), colour = 'blue') +
    geom_line(aes(y = y2), colour = 'green') +
    geom_line(aes(y = y3), colour = 'red') +
    geom_line(aes(y = y4), colour = 'purple') +
    geom_line(aes(y = y5), colour = 'black')

p0 +  geom_area(aes(y = pmin(y1,y2,y3,y4)), fill = 'gray60')
于 2013-01-20T04:40:00.740 回答