Fun histogram tweak

[daviewales]

Set the following options in your ~/.visidatarc for a fun histogram style:

options.disp_histogram = '▇'
options.color_current_row = 'green'

Before:

After:

The colour change is necessary because the default reverse option for color_current_row doesn't look great with the '▇' character.

(Data from https://visidata.org/usage.tsv)

[saulpw]

Neat, @daviewales! Just as a note, you can do:

FreqTableSheet.options.color_current_row = 'green'

and that option will only take effect on the given sheet type.

[daviewales]

So there I was, innocently reading through the Notcurses book, when I encountered the following paragraph in section 7.6 Stupid Unicode Tricks:

Those readers who remember Code Page 437 might recall 0xFD, a “middle half block”. Given a constant
background, this can be used with the other two half blocks to increase “vertical resolution” by a factor of 3
(imagine a tank drawn with upper, middle, and lower half blocks moving on a monochromatic background).
Well, that character was actually “Solid Square/Histogram/Square Bullet” in the CP437 definitions[31], and
lives on as U+25A0 BLACK SQUARE (■). Despite its name, it will take on the foreground color.

I was already thinking of the visidata histogram, and when I read the words "middle half block", I had to try it.
Here is the result:

Before:

After:

It's not perfect, because the block is not quite in the vertical middle, and there's a small gap between each character.
But I think it's pretty close to the best we can get for default visidata, because there's vertical space both above and below which avoids problems with the reverse video line highlight.
And it's a solid improvement over *.

@saulpw, would you consider making this the default character for options.disp_histogram?
(Bonus points if we can squeeze it into 2.11.1!)
I sent through a PR: #1949

(I think I still prefer the lower-7/8-height block with green highlight for my personal use, not least because it adds a splash of colour!)

[anjakefala]

So there I was, innocently reading through the Notcurses book, when I encountered the following paragraph in section 7.6 Stupid Unicode Tricks:

I am not going to be the person making a decision, but I wanted to say that spending time reading a book, hunting for the perfect character, is very good. =)

[daviewales]

Further inspiration for plot functionality:

• https://github.com/red-data-tools/YouPlot
• https://github.com/Martin-Nyaga/termplot
• https://github.com/JuliaPlots/UnicodePlots.jl

[saulpw]

I've been appreciating the new histogram display, @daviewales! It's amazing what a one-character change can do.

[daviewales]

Glad you like it! 😀