velvet and SOAPdenovo assembly

[vani s kulkarni]

hi
I have used the velvet and SOAPdenovo for my solexa reads.
Can any one explain how can I compare cotig from both results?
I have used the same k-mer in both case.

And

I know that people use R for looking at the good contigs (by plotting with k-mer and other parameters), how to do that to judge K-mer or hashlength?

Thanks
vani