## ----setup, include = FALSE---------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  dpi = 300,
  dev = "png"
)

## ----first, fig.height=3.8, fig.width=6, out.width="75%"----------------------
library(gridmicrotex)
library(grid)

latex_options(device_math = TRUE)

plot(1:10, (1:10)^2,
     main = r"(Slope $\hat{\beta}_1 = \sum_{i=1}^{n} x_i^2$)",
     xlab = "Cost $5-$10 per unit",
     ylab = r"($\frac{y}{2}$)")
text(3, 80, r"($\int_0^\infty e^{-x^2}\,dx$)", col = "steelblue")

## ----beyond, fig.height=4.6, fig.width=6.5------------------------------------
set.seed(42)
x   <- seq(0, 3, length.out = 60)
y   <- 2 + 1.4 * x^2 + rnorm(60, sd = 1.1)
fit <- lm(y ~ poly(x, 2, raw = TRUE))
cf  <- signif(coef(summary(fit)), 3)

title_eq <- r"($$\hat{y} = \beta_0 + \beta_1 x + \beta_2 x^2$$)"

# Make room for the tall title
h   <- latex_dims(title_eq, gp = gpar(fontsize = par("ps")))$height
top <- ceiling(convertHeight(h, "bigpts", TRUE) /
               (par("cin")[2] * 72 * par("mex"))) + 2

par(mar = c(4.5, 5.5, top, 2))
plot(x, y, pch = 19, col = "grey45", cex = 0.7, ylim = c(0, 22),
     main = title_eq, xlab = r"($x$)",
     ylab = r"($y = f(x) + \varepsilon$)")
lines(x, predict(fit), col = "#B22222", lwd = 2)

# Build the table as a single line of text
tab <- sprintf(paste0(
  r"(\begin{array}{|l|r|r|}\hline)",
  r"(\rowcolor{#E8F0FE}\text{Term} & \hat{\beta} & \text{SE}\\\hline)",
  r"(\beta_0 & %s & %s\\)",
  r"(\beta_1 & %s & %s\\)",
  r"(\beta_2 & %s & %s\\\hline\end{array})"),
  cf[1, 1], cf[1, 2], cf[2, 1], cf[2, 2], cf[3, 1], cf[3, 2])

text(0.05, 18, tab, adj = c(0, 0.5), cex = 0.75)
text(2.95, 1.2, r"($\varepsilon \sim \mathcal{N}(0, \sigma^2)$)",
     adj = c(1, 0), cex = 0.95, col = "#B22222")

## ----margin-------------------------------------------------------------------
h  <- latex_dims(r"($\frac{a}{b}$)", gp = gpar(fontsize = par("ps")))$height
bp <- convertHeight(h, "bigpts", TRUE)

# Lines of margin needed
bp / (par("cin")[2] * 72 * par("mex"))

## ----off, include = FALSE-----------------------------------------------------
latex_options(device_math = FALSE)