Part VI: ggplot2 introduction

part6.r

## Title: ggplot2 Introduction: Correlation Heatmap
## Description: This line by line analysis, provides an introduction to ggplot2. Correlation Heatmap
## Created by: Brandon Bertelsen: Research Manager, Credo Consulting Inc.

## Heatmap example courtesy of: http://learnr.wordpress.com/2010/01/26/ggplot2-quick-heatmap-plotting/

# Run correlations
e.new <- as.data.frame(cor(e[2:ncol(e)]))
# Reset rownames
e.new <- data.frame(row=rownames(e.new),e.new)
rownames(e.new) <- NULL
# Show
e.new

# Melt
e.new <- melt(e.new)

# Set options for a blank panel
po.nopanel <- list(opts(panel.background=theme_blank(), 
                        panel.grid.minor=theme_blank(), 
                        panel.grid.major=theme_blank()
                        ))

# Plot correlation heatmap
ggplot(e.new, aes(reorder(row,-as.numeric(variable)), variable)) + 
  geom_tile(aes(fill=value)) + 
  scale_fill_gradient(breaks=seq(from=-1, to=1, by=0.25), low="white", high="steelblue") + 
  po.nopanel