在R中绘制椭圆/双曲线 [英] drawing ellipses/hyperbolas in R
问题描述
我想在R中绘制椭圆和双曲线。
如何使用ggplot2来做到这一点?
让我举个例子
I want to draw ellipses, hyperbolas in R. How can I do it using ggplot2? Let me give an example
x^2 +3xy+ 4x+ 2y+ 2y^2 = 0
for
x between -2 and 2
y between -2 and 2
推荐答案
构建数据字段:
Construct a data field:
d <- transform(expand.grid(x=seq(-2,2,length=51),
y=seq(-2,2,length=51)),z=x^2+3*x*y+4*x+2*y+2*y^2)
制作每个级别的基本 geom_contour
图不同颜色:
Make a basic geom_contour
plot with each level coloured differently:
g1 <- qplot(x,y,z=z,data=d,colour=factor(..level..),geom="contour")
现在摆脱所有行0级别。这取决于 stat_contour
选择零作为其轮廓线之一,在某些情况下可能会很脆弱......(这对我来说并不明显, stat_contour ()
允许控制选择哪些级别,相当于级别
参数< contourLines()
在基础R中 - 如果有的话,这个过程会容易一些。 ://github.com/hadley/ggplot2/issuesrel =nofollow noreferrer> https://github.com/hadley/ggplot2/issues ,如果对此有足够的关心......) p>
Now get rid of the lines for all but the "0" level. This depends on stat_contour
picking zero as one of its contour levels, which might be fragile under some circumstances ... (It's not obvious to me that stat_contour()
allows control of what levels are chosen, equivalent to the levels
argument to contour()
or contourLines()
in base R -- if it did, this process would be a little bit easier. One might submit a wishlist item to https://github.com/hadley/ggplot2/issues , if one cared enough about this ...)
g1 + scale_colour_discrete(breaks="0",limits=c("0","0"),na.value=NA,
guide="none")
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