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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！
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))
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))
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)))
目标：
代码：
expression(paste((frac(1, m)+frac(1, n))^-1, ABCD[paste(m, ',', n)]))
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
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 |
感谢各位的阅读，以上就是“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”的内容了，经过本文的学习后，相信大家对怎么用R语言绘图时实现输出希腊字符上下标及数学公式这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是亿速云，小编将为大家推送更多相关知识点的文章，欢迎关注！
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