[R] if - else

[James J. Roper]

Greetings,

I have some confusion with the use of if - else.  Let's say I have a
four variables as follows:

Condition               DateFound          DateFirstEvent
DateSecondEvent
NA                        10Jan2000          NA                             NA
0                           05Jan2000          07Jan2000
   10Jan2000
1                           07Jan2000          07Jan2000
   08Jan2000
2                           09Jan2000          NA                             NA

Now, what I need to do is make a new variable that is either the
midpoint of the first and second event dates, or the date found (I
will call Start).

I tried an if - else condition as follows:

Start <- if (DateFirstEven < DateSecondEvent)
(DateFirstEvent+DateSecondEvent)/2 else DateFound

I also tried

Start <- if (any(DateFirstEven < DateSecondEvent))
(DateFirstEvent+DateSecondEvent)/2 else DateFound

Only the first half of the expression was ever evaluated.

I hope I have not been to brief, and will certainly appreciate any help.

Thanks,

Jim

-- 
James J. Roper
Population Dynamics and Conservation of
Terrestrial Vertebrates
Caixa Postal 19034
81531-990 Curitiba, Paraná, Brasil
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