[Feature Request] Add more control to histograms about plotters

[38]

I don't know if you realized this, series is just a iterator of elements. Basically bar chart can be done with

     ctx.draw_series( 
             data.map(|(bucket, value)| {
                    let rect = Rectangle::new([(bucket - 1, 0), (bucket, value)], BLUE.filled());
                    rect.margin(0, 0, 5, 5); 
                    rect
            })
     );

And of course you can control the color. I am not very satisfy with current implementation of histogram, and I am thinking about some better solution as well. If you have any thoughts, please let me know :)

For your second question, this also can be done by implementing a wrapper for ranged value and you can control what key point you want to emit. The key trait to implement is called Ranged, see docs at https://docs.rs/plotters/0.2.11/plotters/coord/trait.Ranged.html.

The logarithmic coordinate is supported in this way, please see code at https://github.com/38/plotters/blob/master/src/coord/logarithmic.rs.

And of course both suggest make sense to me and please let me think how to make built-in support for these.

[TatriX]

It's not yet clear to me what can passed to draw_series. Currently my brain stops at E: Drawable<DB> from here.
I guess passing some kind of data structure should do the trick:

draw_series(LineSeries::new(data.map(|x, y| Point{x, y, color: Some(rand_color()) }), &RED))

So color defaults to RED but can be overriden by individual data point.

[38]

Hmm, draw_series accepts anything can be converted into a iterator of elements.

An element is actually combination of two trait, one is PointCollection which holds the vertices another one is Drawable<DB> means once the coordinate mapping is done, it can be drawn on to the specific backend.

And anything under element module should be ready to pass into draw_series.

The element system is a little bit undocumented unfortunately, the only doc I have is https://docs.rs/plotters/0.2.11/plotters/element/index.html

[38]

A quick update on this. I changed the histogram API which allows you to passing a closure that retutrns style based on the values.

Check here for details, let me know if this works for you:)

https://github.com/38/plotters/blob/8e99cdd69b9708f571c46d07161048dbcfe344a5/src/series/histogram.rs#L59

[38]

Also, now you can use code like

.build_ranged((0..100).group_by(7), 10..20)?

to make the key point a multiply of 7

[TatriX]

This looks amazing! Will try soon.
BTW, do you have any plans on making range being set in an automatic fashion?
Currently I need to collect data to for example into Vec, then find min/max values and only then I can draw series.

[TatriX]

Yep, both features work like a charm, thanks!