repr does not handle nested dataframes

[jankatins]

# https://blog.rstudio.org/2016/02/02/tidyr-0-4-0/
library(gapminder)
library(dplyr)
library(tidyr)
by_country <- gapminder %>% 
  group_by(continent, country) %>% 
  nest()
print(by_country) # prints ok
by_country # has the content of the data column messed up

One solution could be to add a if df contains a nested df/list/... column, refuse to rich print with a warning...

[I'm not sure if data.frames are allowed to contain nested data-frames, but I do have such a data.frame here coming from a JSON structure:

download.file("http://jsonstudio.com/wp-content/uploads/2014/02/world_bank.zip", "world_bank.zip")
world_bank <- jsonlite::stream_in(unz("world_bank.zip", "world_bank.json"))

]

[jankatins]

tibble uses https://github.com/hadley/tibble/blob/7b7a0c15c527bae75676f7ba786914697bb78b11/R/type-sum.r for the short summeries of nested objects

[flying-sheep]

what is a “nested data frame”? data.frames are lists of vectors of primitive types:

a_data_frame <- structure(
    list(Foo = 1:3, Bar = letters[1:3]),
    class = 'data.frame',
    row.names = paste0('R', 1:3))

so there’s no way to “nest” them. whatever your libraries do there isn’t returning a data.frame

[MichaelChirico]

data.frames are lists of vectors of primitive types:

This is not true. It's quite easy to create nested data.frame structures

DF = data.frame(a=1:10)
DF$l = as.list(DF$a)
DF$nested = data.frame(b = 10:1, c = letters[1:10])
DF$mat = as.matrix(DF$nested)
DF
#     a  l nested.b nested.c mat.b mat.c
# 1   1  1       10        a    10     a
# 2   2  2        9        b     9     b
# 3   3  3        8        c     8     c
# 4   4  4        7        d     7     d
# 5   5  5        6        e     6     e
# 6   6  6        5        f     5     f
# 7   7  7        4        g     4     g
# 8   8  8        3        h     3     h
# 9   9  9        2        i     2     i
# 10 10 10        1        j     1     j

[MichaelChirico]

?data.frame describes the class thus:

The function data.frame() creates data frames, tightly coupled collections of variables which share many of the properties of matrices and of lists, used as the fundamental data structure by most of R's modeling software.

And in Details:

A data frame is a list of variables of the same number of rows with unique row names

?data.frame also explicitly calls out how recursive structures are handled in the data.frame() constructor:

If a list or data frame or matrix is passed to data.frame it is as if each component or column had been passed as a separate argument (except for matrices protected by I).

[flying-sheep]

hm, tidyverse thinks differently about nesting data.frames, but of course repr’s code shouldn’t crash when trying to render either of them. PRs welcome!