How to create geom_bar next to each other from different databases

Question

I'm struggling with trying to create a simple bar graph where the bars are next to each other(like pictured).

The data are from different databases.

Database A
 Month     Cost
1 Dec      3009       
2 Dec      3468       
3 Nov      3420        
4 Oct      3162



Database B
    Month     Cost
1 Dec      309       
2 Nov      3481       
3 Nov      3419        
4 Oct      3120     

For the bar graph, I am trying to show a bar graph that has the X-axis as the month, and for month Dec, A would have 2 (the total count, not the value), B = 1, for month Nov, A would have 1, and B would have 2. Thank you!

Answer 1

You could add an id variable to your datasets, bind them by row and make a standard bar chart where you map id on fill :

db1 <- read.table(text = "Month     Cost
1 Dec      3009       
2 Dec      3468       
3 Nov      3420        
4 Oct      3162", header = TRUE)

db2 <- read.table(text = "Month     Cost
1 Dec      309       
2 Nov      3481       
3 Nov      3419        
4 Oct      3120", header = TRUE)

library(ggplot2)
library(dplyr)

db <- dplyr::bind_rows(list(A = db1, B = db2), .id = "id")
db$Month <- factor(db$Month, levels = month.abb)
ggplot(data = db, mapping = aes(Month, fill = id)) +
  geom_bar(position = "dodge")