Barplot

In this notebook, we will be focusing on creating a barplot in R. As a first step, we will be loading the dataframe and create a table from it.

df <- read.csv('Data/NHANES.csv')
head(df)

count <- table(df$Education)[2:6]
count

## 
##      8th Grade 9 - 11th Grade   College Grad    High School   Some College 
##            451            888           2098           1517           2267

We will be using this table to create a barplot. The basic structure of the code to create a barplot is the following:

barplot(count, xlab='x axis label', main='title')

where count is the table that is created by using the dataframe. xlab is the x-axis label and main is the title of the plot.

barplot(count, xlab='Education level', main='Education in the U.S.')

1. Reordering the barplot

We can easily reorder the barplot by creating levels inside the dataframe. This can be done by using the following code:

df$Education <- factor(df$Education, levels=c('8th Grade','9 - 11th Grade','High School','Some College','College Grad'))
count <- table(df$Education)
count

## 
##      8th Grade 9 - 11th Grade    High School   Some College   College Grad 
##            451            888           1517           2267           2098

We at first factor the items in the column by using:

df$column <- factor(df$column, levels=c('element1','element2',...))

where you put element1, element2, …, based on the order that you would like to show it on the barplot. Then, create a table from that column and make a barplot from the new table:

barplot(count, xlab='Education level', main='Education in the U.S.')

2. Change color

We can change the color of the barplot by adding a col argument inside the code:

barplot(count, xlab='x axis label', main='title', col=`blue`)

change blue based on the color that you would like to have. The list of main colors available in R is:

https://www.r-graph-gallery.com/42-colors-names.html

http://www.stat.columbia.edu/~tzheng/files/Rcolor.pdf

barplot(count, xlab='Education level', main='Education in the U.S.', col='cyan')