Summarise no longer grouping

Question

I think dplyr is awesome. However I recently updated the package and it seems that summarise no longer aggregates by group for me. Something similar to the following code used to summarize by group before the upgrade:

iris_tdt <- tbl_dt(iris)
iris_tdt %.% group_by(Species) %.% summarise(avg_petal_width = mean(Petal.Width))

  avg_petal_width
1        1.199333

This used to output a table with Species and avg_petal_width. Now the Species column seems to be dropped and avg_petal_width is aggregated to a single value. group_by seems to be working, so I'm guessing this is a issue with summarise.

grp <- group_by(iris_tdt,Species)
groups(grp)

[[1]]
Species

Not even the example from the Vignette works correctly.

hflights_df <- tbl_df(hflights)
planes <- group_by(hflights_df, TailNum)
delay <- summarise(planes,
  dist = mean(Distance, na.rm = TRUE),
  delay = mean(ArrDelay, na.rm = TRUE))

delay
      dist    delay
1 787.7832 7.094334

Any advice would be greatly appreciated.

packageDescription("dplyr")$Version #--> 0.1.2
R.version.string #--> "R version 3.0.2 (2013-09-25)"

Answer 1

You may have another summarise function, probably from the plyr package.

# Works
library(dplyr)
iris_tdt <- tbl_dt(iris)
iris_tdt %.% 
  group_by(Species) %.% 
  summarise(avg_petal_width = mean(Petal.Width))

# No longer works...
library(plyr)
iris_tdt <- tbl_dt(iris)
iris_tdt %.% 
  group_by(Species) %.% 
  summarise(avg_petal_width = mean(Petal.Width))

If you really need both packages, you can try to load dplyr last, or prefix all the affected functions (summarise, mutate, etc.) with their namespace (dplyr::summarise, etc.)