ddply -> dplyr: .fun = summarize with several rows

[Sebastian Schubert]

Hi,

I'm rather new to (d)plyr and want to focus on learning the more recent package. However, I failed to translate something like the following to dplyr:

library(plyr)

#library(dplyr)

dfx <- data.frame(

    group = c(rep('A', 8), rep('B', 15), rep('C', 6)),

    sex = sample(c("M", "F"), size = 29, replace = TRUE),

    age = runif(n = 29, min = 18, max = 54)

    )

 

p <- c(.2,.4,.6,.8)

ddply(dfx, .(group), .fun = summarize, p=p, stats=quantile(age,probs=p))

# dfx %>% group_by(group) %>% do(stats=quantile(.$age, probs=p))

The commented lines show what I found working with dplyr. Here, the data structure is more complicated, though. (Don't load dplyr package to have ddply working.)

What can I do to get the same result with dplyr as with ddply?

Thanks a lot,

Sebastian

[Sebastian Schubert]

> library(plyr)
> #library(dplyr)
>
> dfx <- data.frame(
> group = c(rep('A', 8), rep('B', 15), rep('C', 6)),
> sex = sample(c("M", "F"), size = 29, replace = TRUE),
> age = runif(n = 29, min = 18, max = 54)
> )
>
> p <- c(.2,.4,.6,.8)
> ddply(dfx, .(group), .fun = summarize, p=p, stats=quantile(age,probs=p))
> # dfx %>% group_by(group) %>% do(stats=quantile(.$age, probs=p))

I got help on sx:
http://stackoverflow.com/a/24405853/1463740
http://stackoverflow.com/a/24406376/1463740

and the solution is to use unnamed data.frame arguments in do():

dfx %>%
group_by(group) %>%

do(data.frame(p=p, stats=quantile(.$age, probs=p)))

Thanks
Sebastian