Is it possible to add ggplot2 annotations programmatically

Question

I have the following code snippet:

  for(j in 1:10){
    max_value[j] <- round(value * 1.1 ^ j, 2)
    min_value[j] <- round(value * 0.9 ^ j, 2)
    max_estimate[j] <- round(log(max_value[j]) + 0.2775, 3)
    min_estimate[j] <- round(log(min_value[j]) + 0.2775, 3)
  }

gg <- ggplot(data, aes(x = as.Date(rowname), y = get(ticker))) +
      geom_line() +
      # value calulation date vline
      geom_vline(xintercept = date_value, col = "Gray", size = 1) +
      # Index value at value calculation date hline
      geom_hline(yintercept = value_value, col = "Gray", size = 1) +
      # Max values hlines
      geom_hline(yintercept = pre_values_max, col = "Red", size = 1) +
      # value and return estimate for the value calculation date
      annotate("text", as.Date("2013-12-31"), value_value * 1.02,
               label = paste0(value, ", ", percent(return_estimate)), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[1] * 1.02,
               label = paste0(max_value[1], ", ", percent(max_estimate[1])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[2] * 1.02 ^ 1,
               label = paste0(max_value[2], ", ", percent(max_estimate[2])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[3] * 1.02,
               label = paste0(max_value[3], ", ", percent(max_estimate[3])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[4] * 1.02,
               label = paste0(max_value[4], ", ", percent(max_estimate[4])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[5] * 1.02,
               label = paste0(max_value[5], ", ", percent(max_estimate[5])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[6] * 1.02,
               label = paste0(max_value[6], ", ", percent(max_estimate[6])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[7] * 1.02 ^ 1,
               label = paste0(max_value[7], ", ", percent(max_estimate[7])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[8] * 1.02,
               label = paste0(max_value[8], ", ", percent(max_estimate[8])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[9] * 1.02,
               label = paste0(max_value[9], ", ", percent(max_estimate[9])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_max[10] * 1.02,
               label = paste0(max_value[10], ", ", percent(max_estimate[10])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[1] * 1.02,
               label = paste0(min_value[1], ", ", percent(min_estimate[1])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[2] * 1.02,
               label = paste0(min_value[2], ", ", percent(min_estimate[2])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[3] * 1.02,
               label = paste0(min_value[3], ", ", percent(min_estimate[3])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[4] * 1.02,
               label = paste0(min_value[4], ", ", percent(min_estimate[4])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[5] * 1.02,
               label = paste0(min_value[5], ", ", percent(min_estimate[5])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[6] * 1.02,
               label = paste0(min_value[6], ", ", percent(min_estimate[6])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[7] * 1.02,
               label = paste0(min_value[7], ", ", percent(min_estimate[7])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[8] * 1.02,
               label = paste0(min_value[8], ", ", percent(min_estimate[8])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[9] * 1.02,
               label = paste0(min_value[9], ", ", percent(min_estimate[9])), color = "Blue") +
      annotate("text", as.Date("2013-12-31"), pre_values_min[10] * 1.02,
               label = paste0(min_value[10], ", ", percent(min_estimate[10])), color = "Blue") +
      # Min values hlines
      geom_hline(yintercept = pre_values_min, col = "Green", size = 1) +
      ggtitle(paste0(country, ", ", ticker)) +
      xlab("Date") + ylab("Index")
    print(gg)

As you can see, there are 21 annotations, but their values are made in the first loop. Is there a way to programmatically add the annotations? For loops or if-statements don't seem to work inside ggplot. What if I had a hundred of these values, how could the plot be made then, without having a hundred extra rows? Sorry for no reprex, but the code and the objective should be quite clear.

Did you try geom_text_repel from ggrepel?

Naive_Natural2511
– Naive_Natural2511

2018-11-18 18:02:40 +00:00
Commented Nov 18, 2018 at 18:02 — Naive_Natural2511
– Naive_Natural2511, Commented Nov 18, 2018 at 18:02

yrx1702 · Accepted Answer · 2018-11-18 19:49:40Z

1

You can save the plot as character string, add the annotate() lines in a loop and then execute the resulting character string:

library(ggplot2)


data <- data.frame(x=rnorm(100),y=rnorm(100)) #example data
annotations <- data.frame(x=c(-2,-1,-1),      #annotation information
                          y=c(0,1,2),
                          text=c("An. 1","An. 2", "An. 3"))
p <- "ggplot(data, aes(x,y)) + geom_point()"  #save plot as character string

eval(parse( text=p )) #execute character string


for(i in 1:nrow(annotations)){

  #in each iteration, add one annotate line 
  #with info from the annotations dataframe

  p <- paste(p,paste0('+ annotate("text",',annotations[i,1],',',annotations[i,2],', label ="', annotations[i,3],'", color = "Blue")'))


}

eval(parse( text=p )) #new plot with all annotations

answered Nov 18, 2018 at 19:49

yrx1702

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