Boxplots for groups of data

I am trying to plot some boxplots using the grouping variable but I am having little success so far. Perhaps someone can point me into the right direction.

I have

X = zeros(10,4); X(:,1) = rand(10,1); X(:,2) = rand(10,1); X(:,3) = rand(10,1); X(:,4) = rand(10,1);

boxplot(X);

which produces one box plots for each column of X. That works.

Now I want to group the boxplots such that group 1 consists of the first to columns of X and group 2 of the last 2 columns of X.

How can I do that?

The man page says "Grouping variables must have one row per element of X, or one row per column of X." but when I do that I get an error saying: "X must be a vector when there is a grouping variable."

Answer 1

[Star Strider]

The reshape function is your friend here. Create a (20x2) matrix Z from your (20x4) matrix X:

X = rand(10,4)
Z = reshape(X,[],2)

then use Z as your data matrix.