Aggregation by time period in lubridate

Question

This question asks about aggregation by time period in R, what pandas calls resampling. The most useful answer uses the XTS package to group by a given time period, applying

Answer 1

Using ddply from plyr package:

library(plyr)
bikecounts$Date<-with(bikecounts,as.Date(Date, format = "%m/%d/%Y"))
x<-ddply(bikecounts,.(Date),summarise, sumnorth=sum(Northbound),sumsouth=sum(Southbound))


 > head(x)
        Date sumnorth sumsouth
1 2012-10-02     1165      773
2 2012-10-03     1761     1760
3 2012-10-04     1767     1708
4 2012-10-05     1590     1558
5 2012-10-06      926     1080
6 2012-10-07      951     1191


 > tail(x)
          Date sumnorth sumsouth
298 2013-07-26     1964     1999
299 2013-07-27     1212     1289
300 2013-07-28      902     1078
301 2013-07-29     2040     2048
302 2013-07-30     2314     2226
303 2013-07-31     2008     2076