(This article was first published on Taiyun Wei, and kindly contributed to R-bloggers)
See in my Picasa here and get corrplot package here. Thanks Bob O'Hara's advice:)I found people's tastes differ, so input parameter col (fill color) and bg (background color) was added in new edition. What is more, now you can order your variables using PCA (order=TRUE) to get a better impression.
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Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).