Do output control format

Question

The following two statements doprovide slightly different results:

library(dplyr)
set.seed(1)
d <- data.frame(x = rnorm(30), y = rnorm(30), w = factor(sample(3, 30, TRUE)))

(r1 <- d %>% group_by(w) %>%
   do(data.frame(s1 = sum(.$x),
                 s2 = sum(.$y),
                 s3 = {
                    z <- seq_along(.$x)
                    sum(z)
                 })))
# Source: local data frame [3 x 4]
# Groups: w [3]
# 
#        w        s1         s2    s3
#   (fctr)     (dbl)      (dbl) (int)
# 1      1 0.1292572  0.8447634    45
# 2      2 0.2092895  3.3060157    91
# 3      3 2.1351984 -0.1675416    36

(r2 <- d %>% group_by(w) %>%
   do(s1 = sum(.$x),
      s2 = sum(.$y),
      s3 = {
         z <- seq_along(.$x)
         sum(z)
      }))
# Source: local data frame [3 x 4]
# Groups: <by row>
# 
#        w       s1       s2       s3
#   (fctr)    (chr)    (chr)    (chr)
# 1      1 <dbl[1]> <dbl[1]> <int[1]>
# 2      2 <dbl[1]> <dbl[1]> <int[1]>
# 3      3 <dbl[1]> <dbl[1]> <int[1]>

If I want to add a more complex object to the output, I have to rely on the second form:

(r3 <- d %>% group_by(w) %>%
   do(s1 = lm(y ~ x, .),
      s2 = sum(.$y),
      s3 = {
         z <- seq_along(.$x)
         sum(z)
      }))
# Source: local data frame [3 x 4]
# Groups: <by row>
# 
#        w      s1       s2       s3
#   (fctr)   (chr)    (chr)    (chr)
# 1      1 <S3:lm> <dbl[1]> <int[1]>
# 2      2 <S3:lm> <dbl[1]> <int[1]>
# 3      3 <S3:lm> <dbl[1]> <int[1]>

So my question is, is there an elegant way to combine the pleasant output of an unnamed form do(in particular, that vectors are stored as vectors and not as list vectors) with the ability to store also more complex objects with a named version do? The desired result would be something like this without the need for additional ones mutate:

r3 %>% mutate(s2 = unlist(s2), s3 = unlist(s3))
# Source: local data frame [3 x 4]
# Groups: <by row>
# 
#        w      s1         s2    s3
#   (fctr)   (chr)      (dbl) (int)
# 1      1 <S3:lm>  0.8447634    45
# 2      2 <S3:lm>  3.3060157    91
# 3      3 <S3:lm> -0.1675416    36

Edit

This question is apparently no longer valid since in my current version dplyrI get listinstead chr.

, s1, s2 s3 (chr)?

Answer 1

list R I.

r3 <- d %>% group_by(w) %>%
    do(data.frame(s1 = I(list(lm(y ~ x, .))),
                  s2 = sum(.$y),
                  s3 = {
                     z <- seq_along(.$x)
                     sum(z)
                  }))

#Source: local data frame [3 x 4]
#Groups: w [3]

#       w      s1         s2    s3
#  (fctr)   (chr)      (dbl) (int)
#1      1 <S3:lm>  0.8447634    45
#2      2 <S3:lm>  3.3060157    91
#3      3 <S3:lm> -0.1675416    36

( chr ​​print.tbl_df, dplyr 0.5. .)