R语言中的curve函数

女爷i 2022-08-30 01:57 324阅读 0赞

### 文章目录 ###

*  curve函数简介
 *  实例
 *   *  绘制y=x的直线
     *  绘制 y = 2x + 3 的直线
 *  y= 2x + 3
 *   *  幂函数图像
 *  y = x
 *   *  三角函数图像
     *  余切函数

# curve函数简介 #

**curve函数语法格式如下：**

curve(expr, from = NULL, to = NULL, n = 101, add = FALSE, type = "l", xname = "x", xlab = xname, ylab = NULL, log = NULL, xlim = NULL, ...)

**主要的参数如下：**

> expr：函数名称或一个关于变量x的函数表达式；
> 
> from，to：表示绘图的起止范围；
> 
> n：一个整数值，表示x取值的数量；
> 
> add：是一个逻辑值，当为TRUE时，表示将绘图添加到已存在的绘图中；
> 
> type：与plot函数中type含义相同；
> 
> xname：用于x轴变量的名称。
> 
> xlab，ylab：x轴和y轴的标签名称。

# 实例 #

## 绘制y=x的直线 ##

#y=x
    curve(x+0, -10, 10, bty="l", xlab="x1", ylab="y")
    abline(h=0, v=0, lty=2, col="gray")
    text(0.5, -0.5, "0", col="gray")
    text(8, 10, "y = x")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE4MDU1MTY3_size_16_color_FFFFFF_t_70]

## 绘制 y = 2x + 3 的直线 ##

# y= 2x + 3 #

curve(2*x + 3, -10, 10, bty="l", xlab = "x", ylab = "y",  asp = 1)
    abline(h=0, v=0, lty=2, col = "darkgray")
    text(0.8, -0.8, "0", col = "darkgray")
    text(15, 20, "y = 2x + 3")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE4MDU1MTY3_size_16_color_FFFFFF_t_70 1]

## 幂函数图像 ##

# y = x #

curve(x^1,-1.5,2,bty="l",xlab="x",ylab="y",asp=1,ylim=c(-1,1))
    abline(h=0,v=0,lty=2,col="darkgray")
    text(0.1,-0.1,"0",col="darkgray")
    lines(c(0,1,1),c(1,1,0),lty=2,col="red")
    text(1.1,0.95,"1",col="red")
    #y = x ^ 2
    curve(x^2,-1.5,2,add=T,col="blue")
    #y = x ^ 3
    curve(x^3,-1.5,2,add=T,col="orange")
    #y = x ^ (1/2)
    curve(x^(1/2), 0,2,add=T,col="green")
    #y = x ^ (1/3)
    curve(x^(1/3), 0,2,add=T,col="darkgreen")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE4MDU1MTY3_size_16_color_FFFFFF_t_70 2]

## 三角函数图像 ##

#sin(x)
    curve(sin(x),-10,10,bty="l",xlab="x",ylab="y",asp=1)
    #cons(x)
    curve(cos,-10,10,add=T,col="blue")
    #下面是绘制坐标轴和图中红色的线及标签
    abline(h=0,v=0,lty=2,col="darkgray")
    text(0.5,-0.5,"0",col="darkgray")
    lines(c(-pi,-pi),c(1.5,-1.5),col="red",lty=3)
    text(-pi,2.5,expression(-pi),col="darkgray")
    lines(c(-pi/2,-pi/2),c(1.5,-1.5),col="red",lty=3)
    text(-pi/2,2.5,expression(-frac(pi,2)),col="darkgray")
    lines(c(pi/2,pi/2),c(1.5,-1.5),col="red",lty=3)
    text(pi/2,2.5,expression(frac(pi,2)),col="darkgray")
    lines(c(pi,pi),c(1.5,-1.5),col="red",lty=3)
    text(pi,2.5,expression(pi),col="darkgray")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE4MDU1MTY3_size_16_color_FFFFFF_t_70 3]

## 余切函数 ##

curve(1/tan(x),-2*pi,2*pi,col="blue",ylim=c(-6,6),asp=1)
    abline(h=0,v=c(-pi,-pi/2,0,pi/2,pi),lty=2,col="darkgray")
    text(c(-pi+0.5,-pi/2+0.5,0.5,pi/2+0.5,pi+0.5),0.5, c("-π","-π/2",0,"π/2","π"),col="darkgray")

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE4MDU1MTY3_size_16_color_FFFFFF_t_70 4]

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