NAME
Term::Fabulous::Chart::Scale - What the scales of chart axes have in common
SYNOPSIS
use Term::Fabulous::Chart::Scale::Linear;
my $scale = Term::Fabulous::Chart::Scale::Linear->fit( extent => [ 3, 97 ], cells => 21 );
say $scale->min, ' .. ', $scale->max; # 0 .. 100
say join ' ', map { $_->{label} } $scale->ticks; # 0 25 50 75 100
say $scale->position(50); # 0.5DESCRIPTION
A scale maps the values of one axis to positions from 0 (the start of the axis) to 1 (its end) and chooses the ticks shown on it. The chart widgets fit a scale to the data and to the cells the axis has every time they are drawn:
- Term::Fabulous::Chart::Scale::Linear
-
Numbers, evenly spaced ticks at "nice" numbers (1, 2, 2.5 and 5 times a power of ten).
- Term::Fabulous::Chart::Scale::Log
-
Positive numbers on a logarithmic axis, ticks at the powers of the base.
- Term::Fabulous::Chart::Scale::Time
-
Points in time (epoch seconds), ticks at calendar boundaries: whole minutes, hours, days, months, years.
- Term::Fabulous::Chart::Scale::Category
-
Labels, one slot each.
METHODS
min, max
The domain: the values at position 0 and 1.
position
my $t = $scale->position($value);0 for min, 1 for max, values in between in between; values outside the domain lie outside 0 to 1. undef for a value the scale cannot show (zero or less on a logarithmic scale).
value_at
The value at a position; the inverse of position.
ticks
foreach my $tick ( $scale->ticks ) {
my ( $value, $label, $position ) = @$tick{qw(value label position)};
}The ticks in order, as hashes with the value, its label and its position.
tick_count
The number of ticks.
cells, used
The number of cells the scale was fitted to, and the number of cells its ticks span: scales whose ticks are evenly spaced choose them so that each tick falls on a whole cell, and then may span fewer cells than they were given. The chart lays the axis out over used cells, so every grid line lies exactly at its label.
is_band
True for scales that give each value a slot (categories) instead of a point.
contains
True when a value lies within the domain.
kind
linear, log, time or category.