[R] aggregating data with Zoo

[Alfonso Sammassimo]

Is there a way of aggregating 'zoo' daily data according to day of week? eg 
all Thursdays

I came across the 'nextfri' function in the documentation but am unsure how 
to change this so any day of week can be aggregated.

I have used POSIX to arrange the data (not as 'zoo' series) according to day 
of week, but am curious if I've missed if a similar option available with 
zoo.

Thank you for any help,

Alf Sammassimo
Melbourne, Australia