The problem here is that you are loading dplyr first and then plyr, so plyr’s function summarise
is masking dplyr’s function summarise
. When that happens you get this warning:
library(plyr)
Loading required package: plyr
------------------------------------------------------------------------------------------
You have loaded plyr after dplyr - this is likely to cause problems.
If you need functions from both plyr and dplyr, please load plyr first, then dplyr:
library(plyr); library(dplyr)
------------------------------------------------------------------------------------------
Attaching package: ‘plyr’
The following objects are masked from ‘package:dplyr’:
arrange, desc, failwith, id, mutate, summarise, summarize
So in order for your code to work, either detach plyr detach(package:plyr)
or restart R and load plyr first and then dplyr (or load only dplyr):
library(dplyr)
dfx %>% group_by(group, sex) %>%
summarise(mean = round(mean(age), 2), sd = round(sd(age), 2))
Source: local data frame [6 x 4]
Groups: group
group sex mean sd
1 A F 41.51 8.24
2 A M 32.23 11.85
3 B F 38.79 11.93
4 B M 31.00 7.92
5 C F 24.97 7.46
6 C M 36.17 9.11
Or you can explicitly call dplyr’s summarise in your code, so the right function will be called no matter how you load the packages:
dfx %>% group_by(group, sex) %>%
dplyr::summarise(mean = round(mean(age), 2), sd = round(sd(age), 2))