Graphics for Statistics - figures with ggplot - Chapter 3 - Bar Charts, Dot plot, add pic

chapter3

Table of Contents

• 1 Chapter 3
  
  • 1.1 Figure 3.4 - simple bar chart
  • 1.2 Figure 3.5 - simple bar chart
  • 1.3 Figure 3.7

1 Chapter 3

Graphics out of the book Graphics for Statistics and Data Analysis with R by Kevin Keen (book home page)

• here are the data
  

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")

Saving 7 x 6.99 in image

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")

Saving 7 x 6.99 in image

1.3 Figure 3.7

• 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

Author: mandy

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