Removing time series with only zero values from a data frame

Question

I have a data frame with multiple time series identified by uniquer id\'s. I would like to remove any time series that have only 0 values.

The data frame looks as fo

Answer 1

An easy plyr solution would be

ddply(mydat,"id",function(x) if (all(x$value==0)) NULL else x)

(seems to work OK) but there may be a faster solution with data.table ...