Graphics for Statistics - figures with ggplot - Chapter 3
1.1 Figure 3.4 - simple bar chart
1.2 Figure 3.5 - simple bar chart
Graphics out of the book Graphics for Statistics and Data Analysis with R by Kevin Keen (book home page)
item<-c("Canada",
"Mexico",
"Saudi Arabia",
"Venezuela",
"Nigeria")
amount<-c(2460,1538,1394,1273,1120)
amount<-amount/1000
df <- data.frame(item=factor(1:5,labels=item),amount=amount)
barrel <- read.jpeg("barrel.jpg")
1.1 Figure 3.4 - simple bar chart
we use geom_bar to create the bar chart
customizing the y-axis by using scale_y_continuous: limits set the limits, expand defines the multiplicative and additive expansion constants
coord_flip rotates it (so we get a horizontal bar chart)
than we set the background to white
set the colour of the axis lines to black (we have to do this to axis.line not just axis.line.x because of inheritance)
get rid of the vertical axis
set colour of the ticks of the x-axis to black
get rid of the ticks of the y-axis
set the colour of the axis labels to black
change the adjustment of the labels of vertical axis
get rid of the grid lines (they are still visible if one looks carefully)
ggplot(df,aes(y=amount,x=reorder(item,-as.numeric(item)))) +
geom_bar(stat="identity",fill="white",colour="black") +
scale_y_continuous("Millions of Barrels per Day",limits=c(0,2.5),expand=c(0,0)) +
xlab("") +
coord_flip() +
theme(panel.background=element_rect(fill="white"),
axis.line=element_line(colour="black"),
axis.line.y=element_blank(),
axis.ticks.x=element_line(colour="black"),
axis.ticks.y=element_blank(),
axis.text=element_text(colour="black",size=11),
axis.text.y=element_text(hjust=0),
panel.grid=element_blank())
ggsave("fig3_4.png")
1.2 Figure 3.5 - simple bar chart
we use geom_point to create the chart with dots (set the size of the dots to 3)
via geom_segment we add the dotted lines (linetype=3)
customizing the x-axis by using scale_x_continuous: limits set the limits, expand defines the multiplicative and additive expansion constants
set the colour of the axis lines to black (we have to do this to axis.line not just axis.line.x because of inheritance)
get rid of the vertical axis
set colour of the ticks of the x-axis to black
get rid of the ticks of the y-axis
set the colour of the axis labels to black
than we set the background to transparent and the colour of the frame to black (panel.background=element_rect)
get rid of the grid lines (they are still visible if one looks carefully)
get rid of of the title of the y-axis
set the colour and the size of the title of the x-axis to black and 11 respectively
ggplot(df,aes(x=amount,y=item)) +
geom_point(size=3) +
geom_segment(aes(yend=as.numeric(item)),xend=0,linetype=3) +
scale_x_continuous("Millions of Barrels per Day",limits=c(0,2.5),expand=c(0,0)) +
theme(axis.line=element_line(colour="black"),
axis.line.y=element_blank(),
axis.ticks.y=element_blank(),
axis.ticks.x=element_line(colour="black"),
axis.text=element_text(colour="black",size=11),
panel.background=element_rect(fill="transparent",colour="black"),
panel.grid=element_blank(),
axis.title.y=element_blank(),
axis.title.x=element_text(colour="black",size=11)
)
ggsave("fig3_5.png")
the clipart can be downloaded here
we need the ReadImages package for reading this jpeg
we need the grid graphics package to divide the plot and insert to several parts
first we load two additional packages (ReadImages for reading the jpeg and grid for the grid graphics functions)
the next part (definition of the dot chart) is exactly the same as in figure 3.5
load the jpeg with the barrel (barrel <- read.jpeg("barrel.jpg"))
the next commands are part of the grid package, which is the underlying graphics system of ggplot2
grid.newpage moves to a new page
pushViewport adds a new viewport (plotting region) to the page (via x and y one can set the position), beginning in the top left corner, setting the width to 0.6 relative to the page and the height to 0.95; just sets the adjustment
print(p,newpage=F) prints the dot chart in this viewport
popViewport() closes the viewport
create another viewport next to the other one with width 0.4 and the same height
grid.raster inserts the picture of the barrel
grid.text inserts the text
library(grid)
library(ReadImages)
p <- ggplot(df,aes(x=amount,y=reorder(item,amount))) +
geom_point(size=3) +
geom_segment(aes(yend=reorder(item,amount)),xend=0,linetype=3) +
scale_x_continuous("Millions of Barrels per Day",limits=c(0,2.5),expand=c(0,0)) +
theme(axis.line=element_line(colour="black"),
axis.line.y=element_blank(),
axis.ticks.y=element_blank(),
axis.text=element_text(colour="black",size=12),
panel.background=element_rect(fill="white",colour="black"),
panel.grid=element_blank(),
axis.title.y=element_blank(),
axis.title.x=element_text(colour="black",size=11)
)
barrel <- read.jpeg("barrel.jpg")
grid.newpage()
pushViewport(viewport(x=unit(0,"line"),y=unit(1,"npc")-unit(2,"mm"),width=0.6,height=0.95,name="vp1",just=c("left","top")))
print(p,newpage=F)
popViewport()
pushViewport(viewport(x=unit(0.7,"npc"),y=unit(0,"npc"),width=0.4,height=0.95,name="vp1",just=c("left","bottom")))
grid.raster(barrel,width=unit(1,"npc"),just=c("centre","bottom"),x=unit(0.2,"npc"),y=unit(3,"line"))
grid.text("Top Five Importing\nCountries of Crude Oil\nand Petrolium\nProducts in 2007\nfor the united States",x=unit(0.2,"npc"),y=unit(1,"npc")-unit(2,"line"),just=c("center","top"))
savePlot("fig3_7.png")
Date: 2012-09-12 21:56:59 CEST
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