[R] Half of a heatmap

[Rosenfeld, Jeffrey]

I am trying to produce a heatmap of pairwise correlations, but since the matrix is symmetric, I only need either the upper or the lower triangle.  I have scoured the web and R documentation, but I have not been able to find a way to produce such a figure.  Is there a simple way to produce a heat map with only the part above or below the diagonal?


Thank You,

Jeffrey Rosenfeld
Cold Spring Harbor Laboratory