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怎么用R语言绘图时实现输出希腊字符上下标及数学公式

发表于：2025-01-23 作者：千家信息网编辑

千家信息网最后更新 2025年01月23日，这篇文章主要讲解了"怎么用R语言绘图时实现输出希腊字符上下标及数学公式"，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习"怎么用R语言绘图时实现输出希腊字符

千家信息网最后更新 2025年01月23日怎么用R语言绘图时实现输出希腊字符上下标及数学公式

这篇文章主要讲解了"怎么用R语言绘图时实现输出希腊字符上下标及数学公式"，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习"怎么用R语言绘图时实现输出希腊字符上下标及数学公式"吧！

希腊字母

使用希腊字符、上标、下标及数学公式，都需要利用一个函数：_expression()，具体使用方式如下：

plot(cars)title(main = _expression(Sigma))

上下标

_expression()中的下标为[]，上标为^，空格为~，连接符为*。示例代码如下：

plot(cars)title(main = _expression(Sigma[1]~'a'*'n'*'d'~Sigma^2))

paste

想达到上面的效果，我们其实可以使用paste()与_expression()进行组合，不需要上述繁琐的过程，也能够达到我们上述一模一样的输出，并且方便快捷：

plot(cars)title(main = _expression(paste(Sigma[1], ' and ', Sigma^2)))

一个复杂的例子

目标：

代码：

_expression(paste((frac(1, m)+frac(1, n))^-1, ABCD[paste(m, ',', n)]))

进阶

在我们想批量产生大量含有不同变量值的标题时，如果遇到变量与公式的混合输出该如何操作，

可参考前文：R语言绘图公式与变量对象混合拼接实现方法

数学公式

最后的数学公式，只需要在_expression()中进行相应的符号连接即可

具体要求可参考：Mathematical Annotation in R

鉴于其很不稳定，这里将里面的细节搬运过来。

（下表也可以直接在 R help 中搜索 plotmath 获取。）

Syntax	Meaning
x + y	x plus y
x - y	x minus y
x*y	juxtapose x and y
x/y	x forwardslash y
x %±% y	x plus or minus y
x %/% y	x divided by y
x %*% y	x times y
x %.% y	x cdot y
x[i]	x subscript i
x^2	x superscript 2
paste(x, y, z)	juxtapose x, y, and z
sqrt(x)	square root of x
sqrt(x, y)	yth root of x
x == y	x equals y
x != y	x is not equal to y
x < y	x is less than y
x <= y	x is less than or equal to y
x > y	x is greater than y
x >= y	x is greater than or equal to y
!x	not x
x %~~% y	x is approximately equal to y
x %=~% y	x and y are congruent
x %==% y	x is defined as y
x %prop% y	x is proportional to y
x %~% y	x is distributed as y
plain(x)	draw x in normal font
bold(x)	draw x in bold font
italic(x)	draw x in italic font
bolditalic(x)	draw x in bolditalic font
symbol(x)	draw x in symbol font
list(x, y, z)	comma-separated list
…	ellipsis (height varies)
cdots	ellipsis (vertically centred)
ldots	ellipsis (at baseline)
x %subset% y	x is a proper subset of y
x %subseteq% y	x is a subset of y
x %notsubset% y	x is not a subset of y
x %supset% y	x is a proper superset of y
x %supseteq% y	x is a superset of y
x %in% y	x is an element of y
x %notin% y	x is not an element of y
hat(x)	x with a circumflex
tilde(x)	x with a tilde
dot(x)	x with a dot
ring(x)	x with a ring
bar(xy)	xy with bar
widehat(xy)	xy with a wide circumflex
widetilde(xy)	xy with a wide tilde
x %<->% y	x double-arrow y
x %->% y	x right-arrow y
x %<-% y	x left-arrow y
x %up% y	x up-arrow y
x %down% y	x down-arrow y
x %<=>% y	x is equivalent to y
x %=>% y	x implies y
x %<=% y	y implies x
x %dblup% y	x double-up-arrow y
x %dbldown% y	x double-down-arrow y
alpha - omega	Greek symbols
Alpha - Omega	uppercase Greek symbols
theta1, phi1, sigma1, omega1	cursive Greek symbols
Upsilon1	capital upsilon with hook
aleph	first letter of Hebrew alphabet
infinity	infinity symbol
partialdiff	partial differential symbol
nabla	nabla, gradient symbol
32*degree	32 degrees
60*minute	60 minutes of angle
30*second	30 seconds of angle
displaystyle(x)	draw x in normal size (extra spacing)
textstyle(x)	draw x in normal size
scriptstyle(x)	draw x in small size
scriptscriptstyle(x)	draw x in very small size
underline(x)	draw x underlined
x ~~ y	put extra space between x and y
x + phantom(0) + y	leave gap for "0", but don't draw it
x + over(1, phantom(0))	leave vertical gap for "0" (don't draw)
frac(x, y)	x over y
over(x, y)	x over y
atop(x, y)	x over y (no horizontal bar)
sum(x[i], i==1, n)	sum x[i] for i equals 1 to n
prod(plain§(X==x), x)	product of P(X=x) for all values of x
integral(f(x)*dx, a, b)	definite integral of f(x) wrt x
union(A[i], i==1, n)	union of A[i] for i equals 1 to n
intersect(A[i], i==1, n)	intersection of A[i]
lim(f(x), x %->% 0)	limit of f(x) as x tends to 0
min(g(x), x > 0)	minimum of g(x) for x greater than 0
inf(S)	infimum of S
sup(S)	supremum of S
x^y + z	normal operator precedence
x^(y + z)	visible grouping of operands
x^{y + z}	invisible grouping of operands
group("(",list(a, b),"]")	specify left and right delimiters
bgroup("(",atop(x,y),")")	use scalable delimiters
group(lceil, x, rceil)	special delimiters
group(lfloor, x, rfloor)	special delimiters