[R] dataframe

n.vialma at libero.it
Wed, 21 Apr 2010 13:54:44 -0000

Dear list,
I have a question about the selection of Variables in dataframes.
I have a dataframes like this:

CFISCA                       FIRMS
YEAR                    VAR               VALUE
20345                            nike
2005                       EC01                 34
20345                            nike
2006                      EC01                   45
56779                           mediaset
2005                       EC01                 65
64568                           agazzini
2005                       EC01                  78
64568                           agazzini
2006                        EC01                   56
78907                           uniteam
2006                         EC01                    46


what my result should be is a new dataframes which have only firms which have
data in both years (2005,2006)

CFISCA                       FIRMS
YEAR                    VAR               VALUE
20345                            nike
2005                       EC01                 34
20345                            nike
2006                      EC01                   45
64568                           agazzini
2005                       EC01                  78
64568                           agazzini
2006                        EC01                   56


Thanks for your attention!!!