title: How to manipulate different words and letter format just in geom_label part of ggplot?
body: <p>I have been trying to present my Regression result directly inside a plot. Even though I have achieved the main task, now I need to beautify my graph. Please look at my current plot. I'd like to have R (subscript 2) instead of R^2, (italicized 'p')-value instead of p-value, and actual minus sign instead of hyphen(-) in values. </p>
  
  <p>I am thinking something can be changed in geom_label() section of my code to achieve this result. But because of my limited knowledge I am not able to achieve this.</p>
  
  <pre><code>ggplotRegressionr &lt;- function (fit, title_of_graph, n, m) {
  
    require(ggplot2)
  
    ggplot(fit$model, aes_string(x = names(fit$model)[2], y = names(fit$model)[1])) + 
      geom_point() + 
      geom_line() + 
      geom_label(aes(1990, m, hjust = 0, vjust = 0, 
                     label = paste("R^2 = ",signif(summary(fit)$adj.r.squared, 3),"\n",
                                   "Slope =",signif(fit$coef[[2]], 3),"\n",
                                   "p-value =",signif(summary(fit)$coef[2,4], 3)))) +
      stat_smooth(method = "lm", col = "red") + 
      xlab("Year") + ylab("Total Precipitation") +
      labs(title = title_of_graph) + 
      scale_y_continuous(limits = c(0, n)) +
      theme(plot.title = element_text(hjust = 0.5))
  
  }
  </code></pre>
  
  <p>Any help will be greatly appreciated. Thank you very much. </p>
  
  <p>Current graph output:
  <img src="https://i.stack.imgur.com/ogtOK.png" alt="Current graph output i have achieved is in the image"></p>