barplot using ggplot2

Question

I have a data set like this:

cars    trucks  suvs
1          2    4
3          5    4
6          4    6
4          5    6
9          12   16

I'm trying to draw a bar chart for this data. Currently, I can do it with barplot:

barplot(as.matrix(autos_data), main="Autos", 
         ylab= "Total",beside=TRUE, col=rainbow(5))

Generating this graph:

Bar plot

So my questions are: Can I use ggplot2 to draw such a graph? Specifically - how do I use faceting or other options to split the graph by days of the week? If yes, how do I accomplish that? Additionally, how do I use facet to produce a different layout?

-1 for not doing a search for "barplot ggplot2" in the handy search box in the top right of your screen. — Andrie
– Andrie, Commented Apr 27, 2012 at 15:00
I try to search in google and in this site. In fact, I can use ggplot2 to draw bar chart for my original data. Because ggplot2 can count the number for you. The problem is if you already get the count results, how to use ggplot2 to draw bar chart just like general "barplot" command? — boyang
– boyang, Commented Apr 27, 2012 at 15:08
OK, that is more sensible. Now add that additional information to your question, and I shall change my downvote. And also add some sample code, i.e. show what you have done and where you get stuck. — Andrie
– Andrie, Commented Apr 27, 2012 at 15:10
possible duplicate of Create a bar graph with pre-summarized data using ggplot2 — Brian Diggs
– Brian Diggs, Commented Apr 27, 2012 at 17:47

Andrie · Accepted Answer · 2012-04-27 15:12:17Z

35

This has been asked many times before. The answer is that you have to use stat="identity" in geom_bar to tell ggplot not to summarise your data.

dat <- read.table(text="
cars    trucks  suvs
1   2   4
3   5   4
6   4   6
4   5   6
9   12  16", header=TRUE, as.is=TRUE)
dat$day <- factor(c("Mo", "Tu", "We", "Th", "Fr"), 
             levels=c("Mo", "Tu", "We", "Th", "Fr"))

library(reshape2)
library(ggplot2)

mdat <- melt(dat, id.vars="day")
head(mdat)
ggplot(mdat, aes(variable, value, fill=day)) + 
  geom_bar(stat="identity", position="dodge")

enter image description here

answered Apr 27, 2012 at 15:12

Andrie

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Comments

Ben G · Accepted Answer · 2018-08-10 14:50:34Z

Here's with tidyr:

The biggest issue here is that you need convert your data to a tidy format. I highly recommend reading R for Data Science (http://r4ds.had.co.nz/) to get you up and running with tidy data and ggplot.

In general, a good rule of thumb is that if you have to enter multiple instances of the same geom, there's probably a solution in the format of your data which would enable you to put everything in the aes() function within the top level ggplot(). In this case you need to use the gather() to arrange your data appropriately.

library(tidyverse)

# I had some trouble recreating your data, so I just did it myself here
data <- tibble(type = letters[1:9], 
               repeat_1 = abs(rnorm(9)), repeat_2  
               =abs(rnorm(9)), 
               repeat_3 = abs(rnorm(9)))

data_gathered <- data %>%
  gather(repeat_number, value, 2:4)

ggplot(data_gathered, aes(x = type, y = value, fill = repeat_number)) +
geom_col(position = "dodge")

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