Showoff

Showoff provides an interface for consistently formatting an array of n things, e.g. numbers, dates, unitful values. It's used in Gadfly to label axes and keys.

It defines a function called showoff that takes an AbstractArray of some type and returns an array of strings of the same length.

If you want your type to look nice when plotted, just define a showoff function. Here's an example.

import Showoff

immutable Percent
    value::Float64
end

function Showoff.showoff(xs::AbstractArray{Percent})
    return [string(x, "%") for x in showoff([x.value for x in xs])]
end

Now we (and more importantly, Gadfly) can print percentages like:

map(println, showoff([Percent(100 * rand()) for _ in 1:20]))

60.505943%
73.255897%
97.477079%
43.330976%
69.023165%
52.580184%
13.011683%
22.718034%
93.843776%
29.875979%
64.110999%
91.203653%
91.534161%
80.684188%
81.674362%
11.530227%
30.498260%
38.876922%
35.444115%
8.857208%

Notice, that compared to show, these all have the same number of digits trailing the ., and look nice when right-aligned.

When no specialized showoff is defined, it falls back on the show function.