Creating stacked barplots in R using different variables

Question

I am a novice R user, hence the question. I refer to the solution on creating stacked barplots from R programming: creating a stacked bar graph, with variable colors for each stacked bar.

My issue is slightly different. I have 4 column data. The last column is the summed total of the first 3 column. I want to plot bar charts with the following information 1) the summed total value (ie 4th column), 2) each bar is split by the relative contributions of each of the three column.

I was hoping someone could help.

Regards, Bernard

Answer 1

If I understood it rightly, this may do the trick

the following code works well for the example df dataframe

df <-  a   b    c   sum
       1    9   8   18
       3    6   2   11
       1    5   4   10
      23    4   5   32
       5    12  3   20
       2    24  1   27
       1    2   4   7

As you don't want to plot a counter of variables, but the actual value in your dataframe, you need to use the goem_bar(stat="identity") method on ggplot2. Some data manipulation is necessary too. And you don't need a sum column, ggplot does the sum for you.

df <- df[,-ncol(df)]            #drop the last column (assumed to be the sum one)
df$event <- seq.int(nrow(df))   #create a column to indicate which values happaned on the same column for each variable
df <- melt(df, id='event')      #reshape dataframe to make it readable to gpglot

px = ggplot(df, aes(x = event, y = value, fill = variable)) + geom_bar(stat = "identity")
print (px)

this code generates the plot bellow