image, heatmap, contour, persp: functions to generate image-like plots
qqnorm, qqline, qqplot: distribution comparison plots
pairs, coplot: display of multivariant data
Help on these functions
?myfct</span></span>
?plot</span></span>
?par</span></span>
Preferred Input Data Objects
Matrices and data frames
Vectors
Named vectors
Scatter Plots
Basic scatter plots
Sample data set for subsequent plots
All pairs
Plot labels
More examples
Print instead of symbols the row names
Usage of important plotting parameters
Important arguments}
- mar: specifies the margin sizes around the plotting area in order: c(bottom, left, top, right)
- col: color of symbols
- pch: type of symbols, samples: example(points)
- lwd: size of symbols
- cex.*: control font sizes
- For details see ?par
Add a regression line to a plot
Same plot as above, but on log scale
Add a mathematical expression to a plot
Exercise 1
Task 1: Generate scatter plot for first two columns in iris data frame and color dots by its Species column.
Task 2: Use the xlim/ylim arguments to set limits on the x- and y-axes so that all data points are restricted to the left bottom quadrant of the plot.
Structure of iris data set:
Line Plots
Single Data Set
Many Data Sets
Plots line graph for all columns in data frame y. The split.screen function is used in this example in a for loop to overlay several line graphs in the same plot.
Bar Plots
Basics
Error bars
Mirrored bar plot
Histograms
Density Plots}
Pie Charts
Color Selection Utilities
Default color palette and how to change it
The gray function allows to select any type of gray shades by providing values from 0 to 1
Color gradients with colorpanel function from gplots library
Much more on colors in R see Earl Glynn’s color chart
Arranging Several Plots on Single Page
With par(mfrow=c(nrow,ncol)) one can define how several plots are arranged next to each other.
Arranging Plots with Variable Width
The layout function allows to divide the plotting device into variable numbers of rows and columns with the column-widths and the row-heights specified in the respective arguments.
Saving Graphics to Files
After the pdf() command all graphs are redirected to file test.pdf. Works for all common formats similarly: jpeg, png, ps, tiff, …
Generates Scalable Vector Graphics (SVG) files that can be edited in vector graphics programs, such as InkScape.
Exercise 2
Bar plots
Task 1: Calculate the mean values for the \Rfunction{Species} components of the first four columns in the \Rfunction{iris} data set. Organize the results in a matrix where the row names are the unique values from the \Rfunction{iris Species} column and the column names are the same as in the first four \Rfunction{iris} columns.
Task 2: Generate two bar plots: one with stacked bars and one with horizontally arranged bars.