R help - Feb 2010 - Keeping the attributes of an observation

Hey R list,

Can someone help me with following question?

I can create a listing of the unique observations in a dataframe by using:

df <- df [order(df $start),]
df $first_ob[!duplicated(df $ID)] <- "1"
df $first_ob[duplicated(df $ID)] <- "0"

Now I want to hold specific attributes of the first observation for other
(the second or third …) observation of a specific element (named ID).

So for example if I have an element with ID X that is ‘ok’ in the first
observation and ‘not ok’ in the second I want to hold the ‘ok’ in a
therefore specified column. An example of the output would be:

ID    start        first ob    T1        T2
X     1/1/2010    1        ok        ok
X    2/2/2010    0        not ok        ok


Thanks in advance.
Kind regards,

John

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