连接 R 中绘图函数中的点的线 [英] Line connecting the points in the plot function in R

问题描述

我在 R 编程语言的绘图函数中有一个简单的问题.我想在点之间画一条线(虽然第二不是我想要的，但我想要一个连续的情节:

解决方案

您必须对 x 值进行排序:

plot(x, f_x, xlim=range(x), ylim=range(f_x), xlab="x", ylab="y",main = "无噪声数据",pch=16)行(x[order(x)]，f_x[order(x)]，xlim=range(x)，y​​lim=range(f_x)，pch=16)

I have a simple problem in the plot function of R programming language. I want to draw a line between the points (see this link and how to plot in R), however, what I am getting something weird. I want only one point is connected with another point, so that I can see the function in a continuous fashion, however, in my plot points are connected randomly some other points. Please see the second plot.

Below is the code:

x <- runif(100, -1,1) # inputs: uniformly distributed [-1,1]
noise <- rnorm(length(x), 0, 0.2) # normally distributed noise (mean=0, sd=0.2)
f_x <- 8*x^4 - 10*x^2 + x - 4  # f(x), signal without noise
y <- f_x + noise # signal with noise

# plots 
x11()
# plot of noisy data (y)
plot(x, y, xlim=range(x), ylim=range(y), xlab="x", ylab="y", 
     main = "observed noisy data", pch=16)

x11()
# plot of noiseless data (f_x)
plot(x, f_x, xlim=range(x), ylim=range(f_x), xlab="x", ylab="y", 
     main = "noise-less data",pch=16)
lines(x, f_x, xlim=range(x), ylim=range(f_x), pch=16)

# NOTE: I have also tried this (type="l" is supposed to create lines between the points in the right order), but also not working: 
plot(x, f_x, xlim=range(x), ylim=range(f_x), xlab="x", ylab="y", 
     main = "noise-less data", pch=16, type="l")

First plot is correct: While second is not what I want, I want a continuous plot:

解决方案

You have to sort the x values:

plot(x, f_x, xlim=range(x), ylim=range(f_x), xlab="x", ylab="y", 
     main = "noise-less data",pch=16)
lines(x[order(x)], f_x[order(x)], xlim=range(x), ylim=range(f_x), pch=16)

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