Unicode Sparkline

Usage

var UnicodeSparkline = require( '@stdlib/plot/sparklines/unicode' );

UnicodeSparkline( [data,] [options] )

Returns a chart instance.

var chart = new UnicodeSparkline();

The constructor accepts the following options:

• autoRender: boolean indicating whether to re-render on a change event.
• bufferSize: data buffer size. If provided, data is kept in a first-in first-out (FIFO) buffer which cannot exceed the buffer size. Default: +infinity.
• data: chart data.
• description: chart description.
• infinities: boolean flag indicating whether to encode infinite values. Default: false.
• isDefined: accessor function indicating whether a datum is defined.
• label: data label.
• type: chart type. Default: 'column'.
• yMax: maximum value of the y-axis domain. If set to null, the maximum value is computed from the data.
• yMin: minimum value of the y-axis domain. If set to null, the minimum value is computed from the data.

Writable Properties

UnicodeSparkline.prototype.autoRender

Rendering mode. If true, an instance renders on each 'change' event; otherwise, rendering must be triggered manually.

var chart = new UnicodeSparkline();

// Set:
chart.autoRender = false;

// Get:
var mode = chart.autoRender;
// returns false

UnicodeSparkline.prototype.bufferSize

Data buffer size. If set, this specifies the maximum number of data elements which can be rendered. Once the data buffer is full, each new datum results in the oldest datum being removed.

var chart = new UnicodeSparkline();

// Set:
chart.bufferSize = 3;

// Get:
var size = chart.bufferSize;
// returns 3

chart.data = [ 1, 2, 3 ];

var data = chart.data;
// returns [ 1, 2, 3 ]

chart.push( 4 );

data = chart.data;
// returns [ 2, 3, 4 ]

Setting a data buffer size is useful when rendering data streams.

UnicodeSparkline.prototype.data

Chart data. When set, the value must be either array-like or an ndarray and cannot exceed the bufferSize.

var Float64Array = require( '@stdlib/array/float64' );

var chart = new UnicodeSparkline();

// Set:
chart.data = new Float64Array( [ 3.14, 5.0, -3.14, -1.0 ] );

// Get:
var data = chart.data;
// returns [ 3.14, 5.0, -3.14, -1.0 ]

Note that data is copied to an internal data buffer.

UnicodeSparkline.prototype.description

Chart description.

var chart = new UnicodeSparkline();

// Set:
chart.description = 'Daily stock prices for the past 30 days.';

// Get:
var desc = chart.description;
// returns 'Daily stock prices for the past 30 days.'

UnicodeSparkline.prototype.infinities

Boolean flag indicating whether to render infinite values. For certain chart types, when set to false, infinite values are considered missing values. Otherwise, for those same chart types, both positive and negative infinity are encoded as ∞.

var chart = new UnicodeSparkline();

chart.infinities = true;

chart.data = [
    1.0,
    5.0,
    NaN,
    Infinity,
    4.0,
    -Infinity,
    3.0
];

var str = chart.render();
// returns '▁█ ∞▆∞▅'

UnicodeSparkline.prototype.isDefined( d, i )

An accessor function which defines whether a datum is defined. This accessor is used to define how missing values are encoded. When invoked, the function is provided two arguments:

• d: datum
• i: datum index

function isDefined( d ) {
    return ( d !== null );
}

var chart = new UnicodeSparkline();

// Set:
chart.isDefined = isDefined;

// Get:
var fcn = chart.isDefined;
// returns <Function>

The default behavior is dependent on the chart type.

UnicodeSparkline.prototype.label

Data label.

var chart = new UnicodeSparkline();

// Set:
chart.label = 'beep';

// Get:
var label = chart.label;
// returns 'beep'

UnicodeSparkline.prototype.type

Chart type.

var chart = new UnicodeSparkline();

// Set:
chart.type = 'line';

// Get:
var type = chart.type;
// returns 'line'

The following chart types are supported:

• 'column': column chart (e.g., ▃▆▂▄▁▅▅).
• 'line': line chart (e.g., ⡈⠑⠢⠔⠒⠒⠒).
• 'tristate': tristate chart (e.g., ▄▀──▀▄▄▀).
• 'up-down': up/down chart (e.g., ↓↑↑↑↑↓↓↑).
• 'win-loss': win/loss chart (e.g., ┌╵└┴╵╷╷╵).

UnicodeSparkline.prototype.yMin

Minimum value of the y-axis domain. If this value is set to a value other than null, the y-axis lower bound is fixed; otherwise, the minimum value is computed from the chart data.

var chart = new UnicodeSparkline( [ -1.0, 5.0, -3.0, 2.0, -4.0, 4.0, 3.0 ] );

chart.yMin = 0.0;

var str = chart.render();
// returns '▁█▁▄▁▇▅'

UnicodeSparkline.prototype.yMax

Maximum value of the y-axis domain. If this value is set to a value other than null, the y-axis upper bound is fixed; otherwise, the maximum value is computed based on the chart data.

var chart = new UnicodeSparkline( [ -1.0, 5.0, -3.0, 2.0, -4.0, 4.0, 3.0 ] );

chart.yMax = 10.0;

var str = chart.render();
// returns '▃▆▂▄▁▅▅'

Methods

UnicodeSparkline.prototype.push( datum )

Appends data to a chart.

var chart = new UnicodeSparkline( [ 1, 2, 3 ] );

var data = chart.data;
// returns [ 1, 2, 3 ]

chart.push( 4 );

data = chart.data;
// returns [ 1, 2, 3, 4 ]

UnicodeSparkline.prototype.render()

Renders a Unicode sparkline.

var chart = new UnicodeSparkline( [ 1.0, 5.0, 3.0, 2.0, 4.0, 4.0, 3.0 ] );

var str = chart.render();
// returns '▁█▅▃▆▆▅'

// Render a line chart from the same data:
chart.type = 'line';

str = chart.render();
// returns '⡈⠑⠢⠔⠒⠒⠒'

UnicodeSparkline.prototype.toString()

Serializes a Unicode sparkline as a string by calling the render() method.

var chart = new UnicodeSparkline( [ 1.0, 5.0, 3.0, 2.0, 4.0, 4.0, 3.0 ] );

var str = chart.toString();
// returns '▁█▅▃▆▆▅'

Events

'change'

Emitted whenever a property value changes.

var chart = new UnicodeSparkline();

chart.on( 'change', onChange );

function onChange() {
    console.log( 'A property was updated.' );
}

'render'

Emitted whenever a sparkline is rendered.

var chart = new UnicodeSparkline();

chart.on( 'render', onRender );

function onRender( str ) {
    console.log( 'Rendered sparkline: %s', str );
}