Intervals and Financial Charts

Interval charts answer where a span begins and ends. The endpoints may represent time, uncertainty, a daily trading range, or a percentile envelope. Model those meanings explicitly with x1 and x2 or y1 and y2; do not force intervals through a point-value channel.

Choose the comparison#

The definition may receive endpoint fields directly or derive them from typed reducer outputs. In either form, endpoint units must match the scale. Data and Channels defines these interval channel shapes.

Compare open-to-close spans#

This view maps each AAPL trading date to a categorical lane and its Open and Close fields to a horizontal rectangle. Color distinguishes gains from losses, while the endpoints carry the price movement directly.

Keep trading dates stable and lane order explicit. Date labels rely on automatic guide measurement; verify them at the smallest supported width with Responsive Charts.

Preserve uncertainty bounds#

An error bar combines a point estimate, a low-high link, and endpoint ticks. The chart renders the supplied interval; it does not decide whether the bounds are standard deviation, standard error, a confidence interval, or a credible interval.

Name the interval in the chart description or surrounding prose. Compose the link, caps, and point as separate layers using the Rules, Links, Arrows, Vectors, and Ticks reference and Dot and Hexagon Marks.

This example groups contributing observations once with groupBy, emits typed mean and sample-deviation outputs, and derives low and high values in the mark channel accessors. The estimator and singleton policy remain authored chart meaning; no dedicated error-bar mark or prepared endpoint DTO is required.

Encode open, high, low, and close#

A candlestick uses a high-low wick and an open-close body. Directional color is secondary to the body endpoints and should not be the only way to distinguish an increasing period from a decreasing one.

Use one row per period with all four values. Render the wick as a link and the body as a ranged rectangle; preserve missing trading periods on the temporal domain instead of silently inventing observations.

Show an interval over time#

A quantile ribbon combines a prepared lower percentile, median, and upper percentile for each time group. It shows how both location and spread evolve.

Use groupBy with quantile reducers to preserve each time group's source rows, then give the ribbon and median their own marks. Transforms and Reactivity defines the aggregation boundary; Line and Area Marks defines the range-area channels.

Production checks#

• State what each endpoint means and whether the interval is inclusive.
• Use timezones and calendar boundaries intentionally for temporal spans.
• Keep interval semantics in data fields rather than inferring them from color or row order.
• Preserve exact values through a tooltip, table, or textual summary. See Tooltips and Focus.
• Use semantic controls and application state when intervals become editable; see Interactions and Selections.
• Verify essential distinctions without color in Accessibility.

Rectangle channel details are in Bar and Rect Marks.