R语言绘图时输出希腊字符上下标及数学公式实现方法
目录
- 希腊字母
- 上下标
- paste
- 一个复杂的例子
- 进阶
- 数学公式
通常在我们写论文时,所需要的统计图是非常严谨的,里面的希腊字符与上下脚标都必须要严格书写。因此在使用R
绘图时,如何在我们目标图中使用希腊字符、上标、下标及一些数学公式呢?在本博客中我们会进行详细的说明。
后面我们都将以一个最简单的绘图为例,只是将其标题进行修改。
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))
输出:
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))
输出:
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 |
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