### ----------------------------------------------------
### -- Terminal::Graphing::BarChart
### -- Licenses: AGPL-3.0-or-later
### -- Authors: masukomi <masukomi@masukomi.org>
### -- File: README.md
### ----------------------------------------------------
# Terminal::Graphing::BarChart

Terminal::Graphing::BarChart is a simple library to let you produce bar graphs on the command line.
It takes special care to give you good looking output.


![example graph](../readme_images/images/social_media_preview.png)

Currently limited to vertical bar charts. See the end of this document for future plans & contribution guidelines. 


SYNOPSIS
========

## Common Usage Example
```raku
# VERTICAL BAR CHART
use Terminal::Graphing::BarChart::Vertical;

my $x_and_y_axis_graph = Terminal::Graphing::BarChart::Vertical.new(
    data => [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100],
    bar_length => 10,
    x_axis_labels => <a b c d e f g h i j k>,
    y_axis_labels => <0 1 2 3 4 5 6 7 8 9>
);

# to get the string version of the graph
$x_and_y_axis_graph.generate();

# to print the graph to Standard Out
$x_and_y_axis_graph.print();
```

Note that for a _vertical_ graph the 0 x 0 point of this graph is the bottom left corner.
Data and labels start from there and move outwards. BUT for a _horizontal_ graph the 0 x 0 point is the top left corner. 

``` raku

my $horizontal_graph = Terminal::Graphing::BarChart::Horizontal.new(
    data => [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100],
    bar_length => 20,
    x_axis_labels => <a b c d e f g h i j>,
    y_axis_labels => <alpha bravo charlie delta echo foxtrot golf hotel india juliet kilo>
);
# to get the string version of the graph
$horizontal_graph.generate();

# to print the graph to Standard Out
$horizontal_graph.print();
```

There are 3 notable restrictions in the horizontal graph

1. x axis labels can't be longer than 1 character
2. `bar_length` must be evenly divisible by the number of x axis labels.
3. the x axis labels will be spread evenly across `bar_length` characters of width.


Folks using Arabic & other Right-to-Left are encouraged to make a PR
to support reversed graphs.

## Required Attributes
When creating a graph there are two required keys. `bar_length` and `data`.

`bar_length` is how tall or wide you wish the core graph's bars to be (in characters). 
This does not include the additional lines for labels or the lines separating them 
from the graph.

`data` is an array of numbers. Each is expected to be a percentage from 0 to 100. 
100 create a vertical bar `bar_length` lines tall. 0 will create an empty bar.

Note, there _will_ be rounding issues if your `bar_length` is anything other than 
an even multiple of 100. This is ok. 

Just to set expectations, if for example, you specify a `bar_length`
of 10 that means there are only 10 vertical/horizontal elements to each bar. If 
one of your data points is 7 you'll end up with an empty bar because that's 
less than the number needed to activate the 1st element (10). 

## Optional Attributes

`x_axis_labels` This is an array of labels for the x axis.
In the vertical bar chart it must be equal in length 
to the number of data points. If you want some of your bars to be unlabeled
then specify a space for that "label".  In the horizontal bar chart it must be 
a number that's `bar_length` can be evenly divided by. In the horizontal bar
chart they must also be no longer than 1 character.

For the horizontal graph I recommend just making it the same number of elements
as the `bar_length`. That way you can precisely specify where each label appears.


`y_axis_labels` This is an array of labels for the y axis. 
In the vertical bar graph it must be equal in length
to the `bar_length` (one label per row). Again, if you want some of
the points to be unlabeled, you should use a space character. In the horizontal graph it can be less. 

Note that the 0 x 0 point of the vertical graph is the bottom left. So its list 
of `y_axis_labels` will go from bottom up. This corresponds to how the
`data` and `x_axis_labels` go from left to right. In the horizontal bar graph it's top left 
so data moves from that column out.

In the Vertical bar graph you can specify `space_between_columns` This is a
`Bool` which defaults to `True`. If you  set it to `False` the system will _not_
introduce a space between each column.  This works fine, and may be a good
choice if you have a large number of data points, but for short graphs it's
almost always worse looking.

### Advice
From a purely visual perspective it is not recommended that you use 
full words for your `x_axis_labels`. In order to not introduce a false sense
of time compression or similar meaning, every bar gets spread out by the 
length of the longest label.

`y_axis_labels` should be fine regardless of length. They are right-aligned, and 
just shove the graph farther to the right.

I would not recommend generating a vertical graph that's more than 10 characters high.
I would recommend making a horizontal graph that's >=20 characters wide. Otherwise they
look too squished. 

See `vertical-graph-tester.raku` and `horizontal-graph-tester.raku` for examples. 

## Legend

This library does not support generating a legend for your graph.
My advice is to use single letter `x_axis_labels` and then use 
[Prettier::Table](https://github.com/masukomi/Prettier-Table/)
to generate a legend that explains your x axis. 


# Future + Contributing

## Contributing
Please do. All I ask is that you include unit tests that cover whatever changes or additions you make, and that you're fine with your contributions being distributed under the AGPL.

What kind of contributions? New Features, refactored code, more tests, etc.

For best results, please ping me on mastodon (see below) to make sure I see your PR right away.

AUTHOR
======

web: [masukomi](https://masukomi.org)  
mastodon: [@masukomi@connectified.com](https://connectified.com/@masukomi)

COPYRIGHT AND LICENSE
=====================

Copyright 2023 Kay Rhodes (a.k.a. masukomi)

This library is free software; you can redistribute it and/or modify it under the AGPL 3.0 or later. See LICENSE.md for details.


