text函数用来在一张图表上添加文字,只需要指定对应的x和y坐标,以及需要添加的文字内容就可以了 基本用法: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") text(x = 3, y = 3, labels = "text") 效果图如下: 支持同时创建多个text标签 代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") text(x = c(3, 3), y = c(3, 5), labels = c("text", "text")) 效果图如下: 参数调整: col : 设置文字的颜色 代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") 效果图如下: cex : 设置文字的大小 代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") text(x = c(3, 3), y = c(3, 5), labels = c("text", "text"), cex = c( 0.5 , 2 )) 效果图如下: sort : 对文件进行旋转 代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") text(x = 3, y = 3, labels = "text", srt = 45) 效果图如下: adj : 调整文字的位置,一个值时调整的是x轴的位置,如果为两个值时,第一个调整的是x轴的位置,第二个调整的是y轴的位置,可选范围为[0, 1] 对x轴进行调整,代码示例: par(mfrow = c(1,3)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 0") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = 0) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 0.5") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = 0.5) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 1") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = 1) x轴调整的效果图如下: 对y轴进行调整,代码示例: par(mfrow = c(1,3)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 0") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = c(0.5, 0)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 0.5") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = c(0.5, 0.5)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 1") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", adj = c(0.5, 1))
y轴调整的效果图如下: pos: 也是对文字的位置进行调整,不能和adj参数同时使用, 可选值为1, 2, 3, 4, 分别对应下, 上, 左, 右4个方向 代码示例: par(mfrow = c(1, 4)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "pos = 1") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", pos = 1) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "pos = 2") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", pos = 2) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "pos = 3") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", pos = 3) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "adj = 4") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", pos = 4) 效果图如下: offset : 只有和和pos 函数搭配起来才会产生作用,对文字的文字进行调整 代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "pos = 1") 效果图如下: font: 设置文字的格式,1是默认值,就是普通的文字,2代表加粗,3代表斜体, 4代表加粗+斜体, 5只有用来ADOBE的设备上时,才有用 代码示例: par(mfrow = c(1, 5)) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "font = 1") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", font = 1) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "font = 2") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", font = 2) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "font = 3") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", font = 3) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "font = 4") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", font = 4) plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n", main = "font = 5") abline(h = 3, v = 3 , col = "gray", lty = 3) text(x = 3, y = 3, labels = "text", font = 5) 效果图如下: text函数的常见用法和参数就参考上面的例子就够了,当我们想打印数学表达式或者一些特殊符号在图片上是,就需要对lables 参数进行特别设置 对于数据表达式,使用expression 函数将其转化成表达式后,在显示出来会更好 打印一个开平方的表达式,代码示例: plot(1:5, 1:5, xlim = c(0,6), ylim = c (0,6), type = "n") text(x = 3, y = 3, labels = expression(sqrt(x))) 效果图如下: 对于表达式的打印,具体的可以参考 plotmath 函数的帮助文档
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