R语言低级绘图函数-axis

axis函数用来在一张图表上添加轴线，区别于传统的x轴和y轴，axis 允许在上，下，左， 右4个方向添加轴线

以x轴为例，一条轴线包含3个元素，水平的一条横线，叫做axis line , 刻度线， 叫做tick line, 对应的标签 labels

基本用法：

通过side 参数设置需要添加的轴线的方向，从下边开始，沿逆时针方向，数字为1到4

代码示例：

par(oma = c(1, 1, 1, 1), mfrow = c(1, 4))
plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
text(x = 3, y = 3, labels = "side = 1", cex = 2)
box()
axis(side = 1)
plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
text(x = 3, y = 3, labels = "side = 2", cex = 2)
box()
axis(side = 2)
plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
text(x = 3, y = 3, labels = "side = 3", cex = 2)
box()
axis(side = 3)
plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
text(x = 3, y = 3, labels = "side = 4", cex = 2)
box()
axis(side = 4)

效果图如下：

参数设置：

at : 需要添加刻度的数值，默认会根据变量的取值范围计算几个合适的刻度，也可以手工指定

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, at = c(0, 2, 4, 6))

效果图如下：

lables : 指定在刻度上需要标记的内容，默认就是刻度对应的值

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, at = c(0, 2, 4, 6), labels = paste(c(0, 2, 4, 6), "A", sep = ""))

效果图如下：

tick : 逻辑值，是否显示轴线，包括刻度线和对应的轴线， FALSE 表示不显示

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
axis(side = 1, tick = F)

效果图：

line : 轴线的位置

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1)

效果图如下：

lwd : 设置 axis  line 和 tick line  的宽度

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1, lwd = 2)

效果图如下：

lwd.tick : 设置tick line的宽度

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1, lwd = 1, lwd.tick = 2)

效果图如下：

lty : 设置axis line 和tick line的线条类型

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1, lty = 3)

效果图如下：

col  : 设置axis line 和 tick.line 的线条颜色

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1, col = "blue")

效果图如下：

col.ticks  : 设置tick line的颜色 

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, line = 1, col = "blue", col.ticks = "red")

效果图如下：

 pos : 对轴线的位置进行调整，当pos 设置了对应的值之后会覆盖line 参数的值

代码示例：

plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", axes = F)
box()
axis(side = 1, pos = 1)

效果图如下：