Table-like printing of a named-tuple of vectors

[pdeffebach]

As a named-tuple of vectors (along with a vector of named tuples) has become the de-factor "minimal" table, I'm wondering if we can change the printing of a named-tuple of vectors to something slightly more table-like.

Consider the output of predict(m, X, interval = :confidence). Which returns a NamedTuple of Vectors

(prediction = [1.214285714285714, 2.8571428571428568, -2.0714285714285725], lower = [-0.925770635957734; -0.014151609177741165; -5.758060544780381], upper = [3.354342064529162; 5.728437323463455; 1.6152034019232366])

Hard to read. in R we get

r$> predict(m1, as.data.frame(x), interval = "confidence")                 
        fit         lwr      upr
1  1.214286 -0.81513839 3.243710
2  2.857143 -0.01289624 5.727182
3 -2.071429 -5.34377662 1.200919

Much easier to read.

I love named tuples of vectors (see my support here).

A package can't fix this without pretty severe type piracy, so I am filing the issue in base.

[JeffBezanson]

This has come up before --- #24627 --- apparently I was in favor of it :)

[pdeffebach]

Ah cool. Maybe we can hook into the Matrix printing in some way to get the alignments right, etc.

[quinnj]

At one point, I looked into having NamedTuple display switch over to the Dict display code if the output was larger than one line; I really like the "single line" printing of small NamedTuples, but agree that it's pretty unwieldy when they get too big. The problem w/ the Dict approach is that code is kind of split over a few different places and, IMO, not factored to be very re-usable.

[pdeffebach]

Maybe a "general" solution would be to have a named tuple print like a table

a b c
-----
1 2 3

unless the table is too wide then print like a Dict. When printing as a table, arrays go downward.

Then the (a = 1, b = 2, c = 3) printing is reserved for repr.

[quinnj]

The thing I like about going from (a = 1, b = 2, c = 3) to:

(
    a = 1,
    b = 2,
    c = 3
)

is you keep the same characters, it's just different whitespace, so it's still copy/pastable by default.

[StefanKarpinski]

(Yes, except that in the multiline form the last one should also have a trailing comma :)

[pdeffebach]

I've been working with named tuples recently and I noticed that all Parameters.jl does for their printing is call dump. I've been using dump instead of print for named tuples and it's been nice.

So i support Quinn's proposal here.