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Editorial Team
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Asked: 2026-06-14T14:35:49+00:00

I wish to plot a shaded region around a line using ggplot. The two

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I wish to plot a shaded region around a line using ggplot. The two data-sets are not directly related and I am doing some comparison between the two. Basically, I wish to plot the output which results from code below, along with shaded region having minimum and maximum y-axis values as entered in the variables ‘lower_region_values’ and ‘upper_region_values’.

Please help me with this issue.

Reproducible code starts here

library("ggplot2")
plotName <- 'Comparison of latitudinal averages'

xlims <- c(65,80) # x axis extent

input_df <- structure(list(flux = c(0.08733913, 0.1015934, 
      0.1244135, 0.1390303,0.08417182,   0.02371609), 
      model = structure(c(1L, 1L, 1L,1L, 1L, 1L),.Label = 
      c("CASA_GFED_Optimized"),  class = "factor"), lat = 
      c(79, 77, 75, 73, 71, 69)), .Names = c("flux","model",  
      "lat"),row.names = c(NA, -6L), class = "data.frame")

 lower_region_values<-c(-0.002157493,-0.004465291,-0.376925852,
     -0.312737571,-0.327533801,  -0.299551351)

 upper_region_values<-c(1.943331e-06,1.758454e-04,3.183347e-01,
      2.442368e-01,1.206353e-  01,1.572531e-02)

 sd_input_lower$model <- factor(sd_input_lower$model, 
      levels=levels(input_df$model))
 sd_input_upper$model <- factor(sd_input_upper$model, 
      levels=levels(input_df$model))

NEED a shaded region using the values in two vectors: lower_region_values and upper_region_values

 chart <- ggplot(input_df, aes(x=lat, group=model, 
      colour=model, fill=model)) +

# geom_ribbon(data = sd_input_upper, aes(ymin = -sd, ymax=sd), alpha=0.5) +

 geom_line(aes(y=flux), size=1.0) + 
      opts(title=plotName,legend.position='bottom') +
      scale_x_continuous('Latitude',limits=xlims) +   
      scale_y_continuous(expression(paste('Latitudinal average of NEE ', 
      (g~C~m^{-2}/day)))) +
      scale_colour_discrete(name='Model') +
      scale_fill_discrete(name='Model')

 print(chart)
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1 Answer

  1. Editorial Team

    I would add the regions for shading into the same data.frame, because it is easier to do ggplots if they are all in the same object. My resulting plot looks a little funny to me so I think we need to make certain that when we add these regions in, they are matching the x-axis values properly in their rows.

    input_df$lower_region_values<-c(-0.002157493,-0.004465291,-0.376925852,
     -0.312737571,-0.327533801,  -0.299551351)

input_df$upper_region_values<-c(1.943331e-06,1.758454e-04,3.183347e-01,
      2.442368e-01,1.206353e-01,1.572531e-02)

    If I understand your goals correctly, I would basically do what you were doing, but move the aes() around a little: 

    chart<-
      ggplot(input_df, aes(x=lat, y=flux,group=model)) +
      geom_line(size=1.0,colour="red") + 
      opts(title=plotName,legend.position='bottom') +
      scale_x_continuous('Latitude',limits=xlims) +   
      scale_y_continuous(expression(paste('Latitudinal average of NEE ', 
      (g~C~m^{-2}/day)))) +
      geom_ribbon(aes(ymin = lower_region_values, 
      ymax=upper_region_values), colour="blue", fill="blue",alpha=0.5)

 print(chart)

    You seem to be using an older version of ggplot2, so if you’re still learning ggplot, I would update and learn the new one, which has some significant changes.

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