1 LaTex
2 プロットエリアにLaTexを挿入するlatex2exp

1 LaTex

1.1 ギリシャ文字.

\(\alpha, \beta, \gamma, \delta, \epsilon, \varepsilon, \zeta, \eta, \theta\)
```
$\alpha, \beta, \gamma, \delta, \epsilon, \varepsilon, \zeta, \eta, \theta$
```
\(\vartheta, \iota, \kappa, \lambda, \mu, \nu, \xi, \omicron, \pi\)
```
$\vartheta, \iota, \kappa, \lambda, \mu, \nu, \xi, \omicron, \pi$
```
\(\rho, \sigma, \tau, \upsilon, \phi, \chi, \psi, \omega\)
```
$\rho, \sigma, \tau, \upsilon, \phi, \chi, \psi, \omega$
```
\(\Theta, \Xi, \Upsilon, \Gamma, \Phi, \Delta, \Pi, \Lambda, \Psi, \Sigma, \Omega\)
```
$\Theta, \Xi, \Upsilon, \Gamma, \Phi, \Delta, \Pi, \Lambda, \Psi, \Sigma, \Omega$
```

1.2 算術演算子.

\(+\) \(-\) \(\pm\) \(\times\) \(\div\)
```
$+$ $-$ $\pm$ $\times$ $\div$
```
\(\frac{X}{Y}\)
```
$\frac{X}{Y}$
```

1.3 等号,不等号.

\(a \ge b, a \le b, a \gt b, a \lt b\)

 $a \ge b,  a \le b,  a \gt b, a \lt b$

1.4 集合.

\(\in\), \(\ni\), \(\notin\)
```
 $\in$, $\ni$ 
```

1.5 カッコ.

\(\left( \right)\), \(\left[ \right]\), \(\lbrace{ \rbrace}\)

 $\left( \right)$,  $\left[ \right]$, $\lbrace{ \rbrace}$

1.6 上付き,下付き.

\(a^n\), \(X_i\), \(X_{ij}\), \(O_{2}^{.-}\)
```
 $a^n$, $X_i$, $X_{ij}$, $O_{2}^{.-}$ 
```
\(\bar{x}\), \(\hat{x}\), \(\vec{xy}\)
```
 $\bar{x}, \hat{x}, \vec{xy}$ 
```

1.7 総和, 総積.

\(\sum\) \(\prod\)
```
 $\sum$  $\prod$ 
```
\(\sum_{i=1}^nX^2_i\)
```
 $\sum_{i=1}^nX^2_i$ 
```

1.8 数式

\(\left(\frac{X}{Y}\right)\)
```
$\left(\frac{X}{Y}\right)$
```
\(N\left(\mu,\ \sigma^2\right)\)
```
 $N\left(\mu,\ \sigma^2\right)$ 
```
\(Y=\beta_{1}+\beta_{2}X+\epsilon\)
```
 $Y=\beta_{1}+\beta_{2}X+\epsilon$ 
```
\(H(A) = -\sum P(A)log P(A)\)
```
 $H(A) = -\sum P(A)log P(A)$ 
```

\(\frac{1}{\sqrt{2\pi\sigma^2}} \exp\left(-\frac{\left(x-\mu\right)^2}{2\sigma^2}\right)\)

 $\frac{1}{\sqrt{2\pi\sigma^2}} \exp\left(-\frac{\left(x-\mu\right)^2}{2\sigma^2}\right)$

2 プロットエリアにLaTexを挿入する`latex2exp`

latex2exp::TeXで文字列を表現式に変換する.その際バッククォートは二重にしてエスケープする.

library(latex2exp); library(ggplot2)


shannon <- function(x){
  Pi <- x/sum(x)
  - sum(Pi*log2(Pi), na.rm = T)
}

v <- list(pois = rpois(100, 10), norm = rnorm(100, 10), 
          binom = rbinom(100, 100, 0.3), unif = runif(100))
x <- sapply(v, shannon)


# LaTexコマンドの文字列
tex <- '$H(A) = -\\sum P(A)log P(A)$'

# base plot
par(mar = c(4,5,1,1))
plot(x, cex = 3, ylab = latex2exp::TeX(tex))

# ggplot2
d <- data.frame(k = names(x), v =x)
p <- ggplot(d, aes(x = k, y= v)) +
  geom_point(size = 10) + 
  theme_bw() + 
  ylab(latex2exp::TeX(tex)) + xlab("")

print(p)