CODEWITHSUNDEEP
rplotggplot2
Amanda
Amanda

Reputation: 85

plotting two variables on bar graph using ggplot2

I am new to using ggplot2 and i am having trouble plotting a graph. I have looked around on SO but the solutions I found did not work with my data. Here is an example of my DF 

Count1     Count2      Color 
  3         4          Red
  3         6          Green 
  5         2          Red
  2         0          Blue

I would like to just plot this is as a bar graph. I would like the X axis to consist of the colors and I would like to plot both the Count1 and Count2 variables on the y axis. for example, the two bars used to show the green color will go up to the number 3 (for count1) and the number 6 (for count2). Similarly, the red bar will go up to 8 (for count1) and 6 (for count2) Does anyone know how to go about doing this? Thanks!

Upvotes: 0

Views: 1384

Answers (1)

Jeremy Voisey
Jeremy Voisey

Reputation: 1297

Breaking up the answer from @alistaire above, so you can follow what's going on

Your data

color_df <- data.frame(Count1 = c(3,3,5,2), Count2 = c(4,6,2,0), Color = c("Red", "Green", "Red", "Blue"))

Adding up counts for each color

library(dplyr)
sum_df <- color_df %>%
    group_by(Color) %>%
    summarise_all(sum)
sum_df

ggplot needs both counts in one column, with another column describing which is which. Compare sum_df and tidy_df

library(tidyr)
tidy_df <- sum_df %>%
    gather(CountName, Count, -Color)

Finally the plot. Dodge puts them side by side. geom_col uses heights from Count variable. geom_bar would count number of observations itself.

library(ggplot2)
ggplot(tidy_df, aes(x = Color, fill = CountName, y = Count)) +
    geom_col(position = "dodge")

Upvotes: 2

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