spark_bar: Draw a sparkline bar graph with unicode block characters
Description
Rendered using [block elements](https://en.wikipedia.org/wiki/Block_Elements).
In most common fixed width fonts these are rendered wider than regular
characters which means they are not suitable if you need precise alignment.
Usage
spark_bar(x, safe = TRUE)
Arguments
x
A numeric vector between 0 and 1
safe
Nominally there are 8 block elements from 1/8 height to full
height (8/8). However, the half-height and full-height blocks appear
to be rendered inconsistently (possibly due to font substitution).