R曲线，轴在中心

Question

默认情况下，R中的笛卡尔坐标轴位于图的底部和左侧 如何使轴居中，如下图所示？

实施例

## using; data; generated; by; bgoldst;;
## estimate curve
x <- seq(-1,1.5,0.1);
y <- c(1.3,1.32,1.33,1.32,1.25,1.1,0.7,0.5,0.4,0.38,0.4,0.41,0.42,0.43,0.44,0.4,0.3,0.1,0,-0.05,-0.1,-0.15,-0.2,-0.24,-0.28,-0.3);
f <- splinefun(x,y);

## calculate precise points along estimated curve
x <- seq(-1,1.5,0.01);
y <- f(x);
plot(x, y, type = 'l')

Answer 1

@ForrestRStevens对我来说太快了，我太忙于尝试使用样条估计曲线：）

## estimate curve
x <- seq(-1,1.5,0.1);
y <- c(1.3,1.32,1.33,1.32,1.25,1.1,0.7,0.5,0.4,0.38,0.4,0.41,0.42,0.43,0.44,0.4,0.3,0.1,0,-0.05,-0.1,-0.15,-0.2,-0.24,-0.28,-0.3);
f <- splinefun(x,y);

## calculate precise points along estimated curve
x <- seq(-1,1.5,0.01);
y <- f(x);

## precompute limits
xlim <- c(min(x),max(x));
ylim <- c(min(y)-0.4,max(y)+0.2);

## set global plot params
par(xaxs='i',yaxs='i',mar=c(1,1,3,3)+0.1); ## "internal" axis spacing, meaning no extended range, and slightly adjust margins

## draw plot
plot(NA,xlim=xlim,ylim=ylim,axes=F,ann=F); ## set plot bounds, no default ornaments
arrows(c(0,xlim[1]),c(ylim[1],0),c(0,xlim[2]),c(ylim[2],0),0.05); ## draw custom axes
mtext('y',3,1,at=0,las=1,cex=0.8,family='serif'); ## y label
mtext('x',4,1,at=0,las=1,cex=0.8,family='serif'); ## x label
lines(x,y,col='#aaaacc'); ## draw line on top

一般情况下，您可以使用基本图形绘制几乎所有内容，但与使用更复杂的软件包相比，它通常更为复杂，因为您必须手动绘制所有内容。

Answer 2

我认为以下内容可以在基本图形中执行您的操作：

##  Simulate your data:
x <- seq(-3, 3, by=0.01)
y <- 0.5*x - 0.3*x^2 + 0.4*x^3

##  Plot the polynomial function, removing axis ticks and bounding box,
##    as well as the axis labels:
plot(x, y, 
     type="l", 
     xaxt='n', yaxt='n', 
     bty='n', 
     xlab='', ylab='', 
     col="blue")

##  Next add in your axis arrows:
arrows(min(x), 0, max(x), 0, lwd=1, length=0.15)
arrows(0, min(y), 0, max(y), lwd=1, length=0.15)

##  And plot your x/y labels.  Note that if you want them
##    actually at the end of the arrows you would need to 
##    remove the pos= argument and shorten your arrows by
##    a small amount.  To match your original figure, you can
##    alter the x/y coordinate to be the max() instead.
text(0, min(y), "y", pos=2)
text(min(x), 0, "x", pos=3)