R GUI : any suggestion??

Please stop misusing this list, which is about DBMS interfaces in R.
This is the third irrelevant posting from you this month, in each case 
with a misleading and unspecific title.

R-help is the list for basic R questions, and this has nothing to do with 
any 'R GUI' (nor does this list).

There is a posting guide, and it asks you to do your homework.  Try the 
help on the functions aggregate(), by ()and tapply()

Hi

Please suggest me how to implement "Group by" function of SQL in R GUI?

e.g.
input data.frame
x                  y
============
a                10
b                20
a                10
a                10
b                15
b                15
b                20

In o/p i need

x            y
=========
a           30
b           70

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595