Interaction plot for grouped data
[h,AX,bigax] = interactionplot(...)
interactionplot(Y,GROUP) displays the two-factor interaction plot for the
group means of matrix
Y with groups defined by entries in
GROUP, which can be a cell array or a matrix.
Y is a numeric matrix or vector. If
Y is a
matrix, the rows represent different observations and the columns represent replications
of each observation. If
Y is a vector, the rows give the means of
each entry in
GROUP is a cell array,
then each cell of
GROUP must contain a grouping variable that is a
categorical variable, numeric vector, character matrix, string array, or single-column
cell array of character vectors. If
GROUP is a matrix, then its
columns represent different grouping variables. Each grouping variable must have the
same number of rows as
Y. The number of grouping variables must be
greater than 1.
The interaction plot is a matrix plot, with the number of rows and columns both equal to the number of grouping variables. The grouping variable names are printed on the diagonal of the plot matrix. The plot at off-diagonal position (i,j) is the interaction of the two variables whose names are given at row diagonal (i,i) and column diagonal (j,j), respectively.
interactionplot(Y,GROUP,'varnames',VARNAMES) displays the interaction
plot with user-specified grouping variable names
VARNAMES is a character matrix, a string array, or a cell array
of character vectors, one per grouping variable. Default names are
'X2', ... .
[h,AX,bigax] = interactionplot(...) returns
h to the figure window, a matrix
handles to the subplot axes, and a handle
the big (invisible) axes framing the subplots.
Display Interaction Plots
Randomly generate data for a response variable
rng default; % For reproducibility y = randn(1000,1);
Randomly generate data for four three-level factors.
group = ceil(3*rand(1000,4));
Display the interaction plots for the factors and name the factors 'A', 'B', 'C', 'D'.