ggplot_linearity

ggplot_linearity.R

# ggplot with equation

lm_eqn <- function(df, key_y, key_x){
  m<-lm(formula(paste(key_y,"~",key_x)), df)
  eq <- substitute(italic(y) == b %.% italic(x) + a*","~~italic(R)^2~"="~r2,
                   list(a = formatC(coef(m)[1], digits = 4,format="f", flag="#"),
                        b = formatC(coef(m)[2], digits = 4,format = "f", flag="#"),
                        r2 = formatC(summary(m)$r.squared, digits = 4,format = "f", flag="#")))
  as.character(as.expression(eq))
}

ggplot_linearity<-function(df, key_x, key_y, plot_xlab="", plot_ylab=""){
  all <- ggplot(df, aes_string(key_x, key_y)) +
    geom_boxplot(aes_string(group = key_x)) + 
    geom_point(size=2, color="black", alpha=.6, shape=17) +
    geom_smooth(aes(colour = "black"), method='lm', alpha=.2) +
    scale_x_continuous(breaks = round(seq(5, 100, by = 5),1)) +
    scale_y_continuous() +
    xlab(plot_xlab) + ylab(plot_ylab) +
    theme_bw() +
    theme(text = element_text(size=20)) +
    theme(legend.position="none")
  all
  final_plot <- all + geom_text(x=max(df[key_x]/1.75),y=max(df[key_y]/5),
                                 label = lm_eqn(df, key_y, key_x),size=6, parse = TRUE)
  return(final_plot)
}