The document introduces ggplot2, an R package for creating statistical graphics based on the 'grammar of graphics' concept. It outlines its components, such as layers, aesthetic mapping, and provides code examples for plotting economic data including deficits and surpluses. Additional resources and references for ggplot2 are also included.

1. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
ggplot2
Premal P. Vora
fpv@psu.edu
Penn State Harrisburg
PhillyR Users’ Group
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2. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
What and why?
ggplot2 is an R package for creating statistical graphics.
“Grammar of Graphics”, Leland Wilkinson, 2005, Springer.
Philosophy of book
Results of philosophy
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3. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Tufte: “...may well be the best statistical graphic ever
drawn.”
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4. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Who and how?
ggplot2 – Hadley Wickham
Requires R version 2.8 (but...get the latest version)
In R environment:
> install.packages(‘‘ggplot2’’)
> library(ggplot2)
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5. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Components of the grammar
Layers
Data and aesthetic mapping
A statistical transformation
A geometric object
A position adjustment
Scales
Coordinate system
Faceting
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6. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Examples of components
Layers
Data and aesthetic mapping
A statistical transformation
A geometric object
A position adjustment
Scales
Coordinate system
Faceting
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7. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Economics and finance data
> real_deficit[1:5,]
Year value
1 1940 -36.3
2 1941 -59.1
3 1942 -219.1
4 1943 -531.7
5 1944 -501.1
> real_surplus[6:10,]
Year value
6 1945 0.0
7 1946 0.0
8 1947 40.2
9 1948 111.5
10 1949 5.7
> real_snp500_level[1:5,]
Year value
1 1940 131.5920
2 1941 103.9474
3 1942 104.3803
4 1943 113.7427
5 1944 139.9368
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8. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Code + output I
> p <- ggplot(data=real_deficit, aes(Year,value))
> p <- p + geom_bar(stat=”identity”, fill=”Red”)
> p
0
−200
−400
−600
value
−800
−1000
−1200
1940 1950 1960 1970 1980 1990 2000
Year
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9. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Code + output II
> p <- p + geom_bar(data=real_surplus, aes(Year,value),
stat=”identity”, fill=”Blue”)
> p
200
0
−200
−400
value
−600
−800
−1000
−1200
1940 1950 1960 1970 1980 1990 2000
Year
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10. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Code + output III
> p <- p + geom_line(data=real_snp500_level, aes(Year,value))
> p
1500
1000
500
value
0
−500
−1000
1940 1950 1960 1970 1980 1990 2000
Year
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11. Introduction
The crux of ggplot2
Specific example
Resources and conclusions
Further information
Book: “ggplot2: Elegant Graphics for Data Analysis”,
Wickham, Springer, 2009.
Website: http://had.co.nz/ggplot2 has reference materials.
Usenet group: http://groups.google.com/group/ggplot2 –
“...relatively low traffic and is very friendly to new users.”
(Wickham, 2009).
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