Hi everybody,,
I have a question about R function duplicated(). I have spent days try to
figure this out,but I cant find any solution yet. I hope somebody can help
me..
this is my data:

subj=c(1,1,1,2,2,3,3,3,4,4)
response=c('sample','sample','buy','sample','buy','sample','
sample','buy','sample','buy')
product=c(1,2,3,2,2,3,2,1,1,4)
tt=data.frame(subj, response, product)

the data look like this:

 subj response product
1     1   sample       1
2     1   sample       2
3     1      buy          3
4     2   sample       2
5     2         buy       2
6     3   sample       3
7     3   sample       2
8     3         buy       1
9     4  sample       1
10   4       buy        4

I want to create new  column based on the value on response and product
column. if the value on product is duplicated, then  the value on new column
is 1, otherwise is 0.
but I want to add conditional statement that the value on product column
will only be considered as duplicated if the value on response column is
'buy'.
for illustration, the table should look like this:

subj response product newcolumn
1     1   sample       1          0
2     1   sample       2          0
3     1      buy          3          0
4     2   sample       2          0
5     2         buy       2          0
6     3   sample       3          1
7     3   sample       2           1
8     3         buy       1           0
9     4  sample       1            1
10   4       buy       4             0


can somebody help me?
any help will be appreciated.
I am new in this mailing list, so forgive me in advance, If I did not  ask
the question appropriately.

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