Issue #448: Add back in examples for a few plots

[nikosbosse]

Closes #448.

Due to previous changes in add_coverage(), several plots that used quantiles or interval ranges. My "solution" at the time was to simply comment the code out. This PR adds it back in and updates the examples.

The PR is currently blocked by the fact that one function that I used in the example is not currently exported to the user. I didn't want to start using ::: in examples, so I suggest addressing that first before merging this PR.

More broadly speaking, there is a question about whether we want to support the function plot_ranges() at all and what should happen with it. I created an issue for that, #462

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a0f23ed) 81.87% compared to head (db6cd16) 81.87%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #463   +/-   ##
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  Coverage    81.87%   81.87%           
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  Files           20       20           
  Lines         1677     1677           
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  Hits          1373     1373           
  Misses         304      304           

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[nikosbosse]

Summarising what's happening:
The PR adds examples for a few plotting functions back in that were previously commented out, specifically

• plot_interval_coverage()
• plot_quantile_coverage()
• plot_ranges()

As mentioned above, the example for plot_ranges() is a bit hacky as it makes use of an internal function accessed via :::. In #462 you suggested removing plot_ranges() altogether for now. I have a vague sense of "it's bad to remove existing functionality", but I also see that leaving it in means committing to maintaining it in a backwards-compatible way.
My solution to that internal conflict is: I fixed the example code + left it in for now so you can have another look at the example below. If you don't have a sudden change of heart I'll delete it from this PR (already pasted the code to #462) and just merge the rest.

this is the output after running the example code for plot_ranges():

library(ggplot2)
ex <- example_quantile
ex$interval_range <- scoringutils:::get_range_from_quantile(ex$quantile)
scores <- score(ex, metrics = list("wis" = wis))
scores$range <- scores$interval_range
summarised <- summarise_scores(
  scores,
  by = c("model", "target_type", "range")
)
plot_ranges(summarised, x = "model") +
  facet_wrap(~target_type, scales = "free")

[seabbs]

LGTM. See comment for thoughts on plot_ranges/