Spark

Renders a numeric series as a Unicode block-glyph bar chart, using eighth blocks (▁▂▃▄▅▆▇█) per character row to get sub-row vertical resolution across an arbitrary number of text rows.

symfony/tui has no built-in Chart/Sparkline widget — this, plus Bars and ChartWidget (which wraps this class to make it fill its assigned space and react to terminal resizes), is what stands in for one.

Scaled against an absolute zero baseline (value / max), not a relative min-max range: every value here is a non-negative count or duration (requests/s, latency ms), where “zero” is a meaningful, distinct reading — a quiet second should draw no bar, not a token minimum-height bar that makes it look identical to “the smallest amount of something * happened.” Min-max normalization (as a single-glyph sparkline typically uses, to guarantee every column shows some visible signal in the one character it has) would blur exactly that distinction.

Synopsis

final class Spark

Source	Spark.php

Methods

Method	Description
renderBars(array<float> $values, int $height): array<string>
resample(array<float> $values, int $targetColumns): array<float>	Downsamples (bucket-averages) a series to at most $targetColumns values, so a chart always exactly fits its assigned width instead of overflowing or leaving it unused.

renderBars()

public static function renderBars(array<float> $values, int $height): array<string>

Parameter	Type	Description
$values	array``<``float``>
$height	int

Returns array``<``string``> — exactly $height lines, top row first, each one character per value (after Spark::resample() if needed to fit a target width)

resample()

public static function resample(array<float> $values, int $targetColumns): array<float>

Downsamples (bucket-averages) a series to at most $targetColumns values, so a chart always exactly fits its assigned width instead of overflowing or leaving it unused.

Parameter	Type	Description
$values	array``<``float``>
$targetColumns	int

Returns array``<``float``>