How to force the x-axis tick marks to appear at the end of bar in heatmap graph?

Question

I created a simple heatmap graph with ggplot2 but I need to force the x-axis tick marks to appear at the end of my x variable, rather than at its center. F

Answer 1

What about this?

object = qplot(x=x, y=y, 
      fill=fill, 
      data=df, 
      geom="tile")+  
      scale_x_continuous(breaks=seq(1:3))

object + scale_x_continuous(breaks=seq(.5,3.5,1), labels=0:3)