[R] flag a record

[Ashta]

 Hi all,

 I have a data set represented by the following sample.

I want flag records of an individual as "N", if  if the tag column of
an individual  is equal to zero for the last  two years. So in the
following example, Alex1 records are flagged as "y",  On the other
hand Carla's records are flagged as "N" because all values of tag  for
Carla are zero. Another typical example is that Jon,  although the tag
values of Jon are greater than 0 it is flagged as "N", because his
record  are more than two years old.

DF <- read.table(textConnection(" Name  year  tag
Alex1    2011         0
Alex1    2012         1
Alex1    2013         0
Alex1    2014         1

Carla     2013      0
Carla     2014      0
Carla     2015      0
Carla     2012      0

Tom     2014       1
Tom     2015       1

 Jon      2010      1
 Jon     2011       1    "),header = TRUE)

I want create another variable " Flag  with value Y or  N"  if an
individual has a  value greater than 0 in the tag column  for the last
two years  then  the flag value will be y otherwise  it n.


the outcome will be
  name   year      tag    Flag
Alex1    2011         0      y
Alex1    2012         1      y
Alex1    2013         0      y
Alex1    2014         1      y

Carla     2013      0         n
Carla     2014      0         n
Carla     2015      0         n
Carla     2012      0         n

Tom     2014       1          y
Tom     2015       1          y

 Jon     2010       1          n
 Jon     2011       1           n

Thank you in advance