Extracting some rows from a data frame - lapses into a vector

I have a data frame with one column "x":

str(data)

`data.frame':   20 obs. of  1 variable:
 $ x: num  0.0495 0.0986 0.9662 0.7501 0.8621 ...

Normally, I know that the notation dataframe[indexes,] gives you a new
data frame which is the specified set of rows. But I find:

str(data[1:10,])

num [1:10] 0.0495 0.0986 0.9662 0.7501 0.8621 ...

Here, it looks like the operation
      data[1:10,]
has converted it from type data frame into a numeric vector. Why does
this happen, and what can I do about it?

Ajay Shah                                                   Consultant
ajayshah at mayin.org                      Department of Economic Affairs
http://www.mayin.org/ajayshah           Ministry of Finance, New Delhi