a barplot with two different variables on R

Question

would like to plot the following data on the same barplot. it is a length frequency barplot showing the males and the females of a population with respect to their length classes:

I am new to this and i dont know how to put my data here, but here is an example:

Lengthclass Both    Males   Females
60  7   5   2
70  10  5   5
80  11  6   5
90  4   2   2
100 3   3   0
110 3   0   3
120 1   1   0
130 0   0   0
140 1   0   1
150 2   0   2

If i use this code: {barplot()} it does not give me all three variables on the same plot.

i need a graph the looks like this but on R.

Thank you:)

Answer 1

classes <- levels(cut(60:100, breaks = c(60,70,80,90,100),
                      right =FALSE))

my.df <- data.frame(lengthclass = classes,
                     both = c(7,10,11,4),
                     male = c(5,5,6,2),
                     female = c(2,5,5,2))

barplot(t(as.matrix(my.df[, 2:4])), 
        beside = TRUE,
        names.arg = my.df$lengthclass,
        legend.text = TRUE,
        ylim = c(0,12),
        ylab = "number of individuals",
        xlab = "Length class (cm)")

Answer 2

Your barplot is known as a "grouped barplot" (in contrast to a "stacked barplot").

Arrange your data in a matrix and use beside=TRUE in your call to barplot(). Here is an example using a built-in dataset:

> VADeaths
      Rural Male Rural Female Urban Male Urban Female
50-54       11.7          8.7       15.4          8.4
55-59       18.1         11.7       24.3         13.6
60-64       26.9         20.3       37.0         19.3
65-69       41.0         30.9       54.6         35.1
70-74       66.0         54.3       71.1         50.0
> barplot(VADeaths,beside=TRUE)