Difference between revisions of "R Histogram & Boxplot of Grades"
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The grades are saved in a txt file, 1 grade per line. Here's a [[List of grades between 0 and 100| typical list]] | The grades are saved in a txt file, 1 grade per line. Here's a [[List of grades between 0 and 100| typical list]] | ||
| + | <br /> | ||
| + | =R Script= | ||
| + | <br /> | ||
| + | <source lang="R"> | ||
| + | # set working directory | ||
| + | setwd( "/Users/thiebaut/Desktop/Dropbox/111/" ) | ||
| + | |||
| + | # read the grades, 1 per line, and make grades numeric | ||
| + | g <- read.table( "midtermGrades.txt" ) | ||
| + | gg <- sapply( g, as.numeric) | ||
| + | |||
| + | # create a layout with boxplot at bottom | ||
| + | nf <- layout( mat = matrix(c(1,2),2,1, byrow=TRUE), height = c(3,1)) | ||
| + | # set parameters | ||
| + | par( mar=c(3.1, 3.1, 1.1, 2.1) ) | ||
| + | |||
| + | # display histogram | ||
| + | hist <- hist( gg, main="Histogram of CSC111 Midterm", col="lightgreen", breaks=17, xaxt='n') | ||
| + | axis(2) | ||
| + | axis(side=1, at=seq( 20,100,5)) | ||
| + | |||
| + | # display boxplot | ||
| + | B <- boxplot( gg, horizontal=TRUE, outline=TRUE, frame=FALSE, col="green", notch=TRUE, width=40) | ||
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| + | |||
| + | |||
| + | </source> | ||
| + | <br /> | ||
| + | =Output= | ||
| + | <br /> | ||
| + | <center>[[Image:HistogramBoxPlotGrades.png|700px]]</center> | ||
| + | <br /> | ||
| + | <br /> | ||
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| + | [[Category:Tutorials]][[Category:R]] | ||
Revision as of 09:49, 22 March 2015
--D. Thiebaut (talk) 10:45, 22 March 2015 (EDT)
This is a simple recipe for generating a histogram and boxplot of student grades. For a much fancier solution, please see the R ProfessR package created and maintained by Prof. Jonathan M. Lees at UNC.
Data
The grades are saved in a txt file, 1 grade per line. Here's a typical list
R Script
# set working directory
setwd( "/Users/thiebaut/Desktop/Dropbox/111/" )
# read the grades, 1 per line, and make grades numeric
g <- read.table( "midtermGrades.txt" )
gg <- sapply( g, as.numeric)
# create a layout with boxplot at bottom
nf <- layout( mat = matrix(c(1,2),2,1, byrow=TRUE), height = c(3,1))
# set parameters
par( mar=c(3.1, 3.1, 1.1, 2.1) )
# display histogram
hist <- hist( gg, main="Histogram of CSC111 Midterm", col="lightgreen", breaks=17, xaxt='n')
axis(2)
axis(side=1, at=seq( 20,100,5))
# display boxplot
B <- boxplot( gg, horizontal=TRUE, outline=TRUE, frame=FALSE, col="green", notch=TRUE, width=40)
Output
