O Christmas tree, O Christmas tree, Last year a fractal made thee! O Christmas tree, O Christmas tree, A heat map can display thee! O tree of green, adorned with lights! A trunk of brown, the rest is white. O Christmas tree, O Christmas tree, A heat map can display
Recently a SAS/IML programmer asked a question regarding how to perform matrix arithmetic when some of the data are in vectors and other are in matrices. The programmer wanted to add the following matrices: The problem was that the numbers in the first two matrices were stored in vectors. The
A heat map is a graphical representation of a matrix that uses colors to represent values in the matrix cells. Heat maps often reveal the structure of a matrix. There are three common applications of visualizing matrices with heat maps: Visualizing a correlation or covariance matrix reveals relationships between variables.
When learning a new language, it is important to learn to interpret error messages that come from the language's parser or compiler. Three years ago I blogged about how to interpret SAS/IML error messages. However, many questions have been posted to the SAS/IML Support Community that indicate that some people
As the International Year of Statistics comes to a close, I've been reflecting on the role statistics plays in our modern society. Of course, statistics provides estimates, forecasts, and the like, but to me the great contribution of statistics is that it enables us to deal with uncertainty in a
Each year my siblings choose names for a Christmas gift exchange. It is not unusual for a sibling to pick her own name, whereupon the name is replaced into the hat and a new name is drawn. In fact, that "glitch" in the drawing process was a motivation for me
If you write an n x p matrix from PROC IML to a SAS data set, you'll get a data set with n rows and p columns. For some applications, it is more convenient to write the matrix in a "long format" with np observations and three columns. The first
