Chapter 6: Graphical Parameters

6.1 Defining Colours

par(mfrow=c(1,1),mar=c(3,0,2,0))
x <- rep(1:8)
y <- rep(1, times = 8)
plot(x,y, col= 1:8, pch= 15, cex= 3, ylim= c(0,2), yaxt= "n",
     main= "Colour Numbers in R: 'col = 1 to 8'")

## Defining Symbols (Points)

# default point types by number
  pch= 1                  # circle outline
  pch= c(1,2,3)           # vector of points 1,2,3
  pch= c(1:3)             # range of points 1 to 3 - same as above
  
# setting points as characters
  pch= "A"            
  pch= c("N","S","E","W")
  
# point size (cex)
  pch= 1 
  cex= 0.5               # circle outline, 50% the default size
  pch= c(1,2,3) 
  cex= 1.2               # points 1,2,3, all 20% larger than default 
  
# add colour (col,bg)
  pch= 1 
  col= 4                 # blue circle outline
  pch= 21 
  col= 3 
  bg= 1                  # filled green circle with black outline
  
# combine parameters
# points 1,2,5 all 20% larger, and using colours 2 to 4
  pch= c(1,2,5)
  cex= 1.2
  col= c(2:4) 
# the most common situation for changing the points is for a scatter plot. 
# For example:

with(mtcars, plot(gear ~ disp, pch= 21,  cex= 1, col=3, bg=9))

6.3 Defining Line Types

# line type
  lty= 1               # solid line
  lty= c(1,5,3)        # list of lines 1,5,3
  lty= c(1:6)          # range of points 1 to 3 - same as above
  
# line width
  lty= 1
  lwd= 0.5             # solid lines, 50% default size
  lty= c(1,2,3)
  lwd= 1.2             # lines 1,2,3, all 20% larger
  
# add colour
  lty= 1
  col= 4               # blue solid line
  lty= c(1,5)
  col= c(3,4)          # green solid and blue dashed lines
  
# combine all parameters
# lines 1,2,3, all red, and using line widths 2 to 4
  lty= c(1,2,3)
  col= 2
  lwd= c(2:4)
  
#  the most common situation for controlling the line type is adding 
#  the trend line to a scatter plot.  For example:
plot(mtcars$gear)
abline(v = c(10,20), col = c(5,2), lty= c(2,2), lwd= c(2,3))

6.4 Saving Plots

#1. Create an empty file in your working directory with your 
#   specified parameters
png("Figure1.png", width = 100, height = 100, units = 'mm', res = 300)
#2. Create your plot
with(PlantGrowth,hist(weight,
      xlim= c(3,7),                       # set the x-axis range
      ylim= c(0,10),                      # set the y-axis range
      col= "beige",                   # fill the columns
      border= "black",                    # column border
      main= "Histogram of Plant Weights", # figure title
      xlab= "Dried weight (g)",           # x-axis label
      ylab= "Frequency"))                 # y-axis label