Is there a way to see the content of a list column in the console?

General
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1

Hello there,

List-columns are really the best thing in the world, but I wonder if there is a way to see in the terminal (at least) the beginning of the contents of my list column.

Say,

frame <- data_frame(mylist = list(list('hello', 'there'), list('hello', 'world')),
                    value = c(1, 2))

> frame
# A tibble: 2 x 2
  mylist     value
  <list>     <dbl>
1 <list [2]>     1
2 <list [2]>     2

Here I have no idea what's inside the list. Can I tweak pillar or tibble so that the column mylist would appear as list('hello', 'there') even at the cost of truncating the output?

Something like

> frame
# A tibble: 2 x 2
  mylist                 value
  <chr>                  <dbl>
1 list('hello', 'there')     1
2 list('hello', 'world')     2

That would be much more useful that having to use listviewer::jsonedit all the time :slight_smile:
Thanks!

2

I don't know about customisation using pillar but glimpse in dplyr can help.

library(dplyr)
glimpse(frame)
#> Observations: 2
#> Variables: 2
#> $ mylist <list> [["hello", "there"], ["hello", "world"]]
#> $ value  <dbl> 1, 2

Created on 2018-08-29 by the reprex package (v0.2.0).

3

thanks @cderv but i was thinking more of something that would tweak the printing directly

4

You can create custom print methods for tibble:
https://tibble.tidyverse.org/articles/extending.html

There are also some specialized print methods in some packages, I don't know much more than that about them, though:
http://library.open.oregonstate.edu/computationalbiology/chapter/objects-and-classes-in-r/

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5

ha!! thanks mara! that looks pretty neat but do you have any idea how that could work here? the customization code looks pretty involved...

6

Like cderv suggested, glimpse() is helpful here, you could also use str().

If you want things to print a certain way without using a function, I think that's precisely what customized print methods are for. The fixing list columns section goes into more detail: https://tibble.tidyverse.org/articles/extending.html#fixing-list-columns

1 Like
7

Part of the difficulty of printing a list column is that every list looks different :frowning: You could write a print method, but it'd be difficult to write one that'd be useful for any old list column :confused:

3 Likes
8

yeah, that is true. somehow i would like to print whatever would show up in the terminal after str... but perhaps mara is right the easiest would be to play around with glimpse...