How to make barplot bars with the same bar width in R

Problem

We have three barplots with a different number of bars in each of them, and we want them to have the same bar width.

par(mfrow=c(1,3));
par(mar=c(9,6,4,2)+0.1);
barcenter1<- barplot(c(1,2,3,4,5));
mtext("Average Emergent", side=2, line=4);
par(mar=c(9,2,4,2)+0.1);
barcenter2<- barplot(c(1,2,3));
par(mar=c(9,2,4,2)+0.1);
barcenter3<- barplot(c(1,2,3,4,5,6,7));

Solution

• First try

Using the arguments xlim = c(0, 1), width = 0.1 the problem is partially corrected. However, you can notice that the bar width is not exactly the same.

width - optional vector of bar widths. Re-cycled to length the number of bars drawn. Specifying a single value will have no visible effect unless xlim is specified.

par(mfrow = c(1, 3))
par(mar = c(9, 6, 4, 2) + 0.1)
barcenter1 <- barplot(c(1, 2, 3, 4, 5), xlim = c(0, 1), width = 0.1)
mtext("Average Emergent", side = 2, line = 4)
par(mar = c(9, 2, 4, 2) + 0.1)
barcenter2 <- barplot(c(1, 2, 3), xlim = c(0, 1), width = 0.1)
par(mar = c(9, 2, 4, 2) + 0.1)
barcenter1 <- barplot(c(1, 2, 3, 4, 5, 6, 7), xlim = c(0, 1), width = 0.1)


• Second try/li>

  We add zeros as placeholders.

  par(mfrow = c(1, 1)) # Reiniciamos los parámetros gráficos
  df <- data.frame(barcenter1 = c(1, 2, 3, 4, 5, 0, 0), 
                   barcenter2 = c(1, 2, 3, 0, 0, 0, 0), 
                   barcenter3 = c(1, 2, 3, 4, 5, 6, 7))
  barplot(as.matrix(df), beside = TRUE)
  

  
  With ggplot2:

  df <- data.frame(x = c(1, 2, 3, 4, 5, 1, 2, 3, 1, 2, 3, 4, 5, 6, 7), 
                   y = c(rep("bar1", 5), rep("bar2", 3), rep("bar3", 7)))                                                                                         
  library(ggplot2)
  ggplot(data = df, aes(x = x, y = x)) + 
    geom_bar(stat = "identity") + 
    facet_grid(~y) 
  

  

Alternative

If instead of three separate barplots we'd like to plot them with an empty space between them, we plot a single barplot with two NAs as delimiters. Si en lugar de tres gráficos propiamente dichos queremos mostrarlos sin que haya separación por las barras en blanco entre ellas, creamos un gráfico único con espacio con dos separaciones por NAs.

x <- c(1, 2, 3, 4, 5, NA, 1, 2, 3, NA, 1, 2, 3, 4, 5, 6, 7)
barplot(x)

References

• Stackoverflow
• Set or Query Graphical Parameters