caculate correlation

Hi Elham,

Hi Dear Jim,

I did it, both return a vector of name of the genes with different length,as
I said before I have list of coding and noncoding so the length are not
same.

where is number?!

Not in the values you are extracting from the data frame. As you are
aware, you can only perform the "cor" operation on numbers. As the
value returned refers to the correlation of _pairs_ of values, the
vectors of numbers should be the same length and there should be some
meaningful relationship between those pairs. Are you just trying to
correlate any old numbers because they are numbers?

and at the end of print there is this error :

<0 rows> (or 0-length row.names)

This is probably not an error, just R telling you that something that
was requested didn't have anything in it. Maybe one day we will find
out what is in:

coding.rpkm
ncoding.rpkm

and we can provide more informed advice.

Jim