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Charts

A Chart presents calculated values visually within an ROI Model.

Use Charts when comparisons, proportions, patterns or changes across a series are easier to understand visually than as individual numerical Outputs.

Ekphrastic provides one Chart component with five available Chart types:

  • Pie Chart

  • Bar Chart

  • Polar Area Chart

  • Area Chart

  • Line Chart

The appropriate Chart depends on the relationship between the values you want to communicate.

Adding a Chart

From Components, under Outputs, select:

Chart

Use Select Chart to choose the required Chart type.

You can then configure the Chart's data sources and presentation.

Choosing a Chart Type

Chart
Useful for

Pie Chart

Showing how individual values contribute to a whole

Bar Chart

Comparing values across categories

Polar Area Chart

Comparing categories in a radial presentation

Area Chart

Showing values across a sequence of labelled points with visual emphasis on magnitude

Line Chart

Showing values across a sequence of labelled points or series

The five Chart types fall into two broad families.

Pie, Bar and Polar Area Charts are constructed from individual segments.

Line and Area Charts use labelled points and can contain one or more series.

Pie, Bar & Polar Area Charts

Pie, Bar and Polar Area Charts are built from individual data segments.

Each segment can have:

  • Legend

  • Chart Segment Color

  • Decimal

  • Formula

Expand Data Source to configure the Formula used to calculate the segment's value.

You can add additional segments or remove existing ones.

At least one segment must remain.

Adding Segments

When you add another segment, Ekphrastic initially copies the Formula from the preceding segment.

You can then change the:

  • Legend;

  • colour;

  • decimal setting;

  • Formula;

for the new segment.

This can make it faster to build Charts containing related calculations.

Segment Chart Preview

Pie, Bar and Polar Area Charts require at least two data sources before a meaningful Chart preview can be displayed.

Until then, you may see:

No Chart preview to display You need 2 or more data sources.

Add and configure another data source to generate the preview.

Line & Area Charts

Line and Area Charts organise values across labelled points on an X axis.

Configure:

Number Of Values

This determines how many points are available within each series.

You can then define the corresponding labels:

  • Label 1

  • Label 2

  • Label 3

  • and so on.

Each series has its own:

  • Legend;

  • colour;

  • Formula for each point.

The individual point calculations are configured through:

  • Data Source 1

  • Data Source 2

  • Data Source 3

  • and so on.

This allows each position within a series to calculate a different value.

Multiple Series

Line and Area Charts can contain multiple series.

Use multiple series when you want to compare different sets of calculated results across the same labelled points.

For example, a Chart could compare two scenarios across the same sequence of periods.

When adding another series, Ekphrastic initially copies the Formulas from the preceding series.

You can then modify the new series as required.

Chart Formulas

Chart data sources use the Ekphrastic Formula Editor.

Chart Formulas can reference eligible:

  • Inputs;

  • Outputs.

This allows Chart values to respond dynamically as users change Inputs within the ROI Model.

Charts cannot use:

  • another Chart;

  • a Table Formula Output;

as a Formula source.

A Chart also cannot itself be referenced as a Formula source by another component.

Using index in Chart Formulas

Chart calculations provide an additional Formula token:

index

index represents the position of the current data point or segment.

It is 1-based, meaning:

  • first point = 1

  • second point = 2

  • third point = 3

  • fourth point = 4

and so on.

The index token can be used within:

  • Pie Chart segments;

  • Bar Chart segments;

  • Polar Area Chart segments;

  • Line Chart points;

  • Area Chart points.

When index Is Useful

Use index when a calculation needs to change according to the position of a Chart data point.

For example, a Formula could use index as part of a calculation that changes across a sequence of periods.

Each point or segment has its own Formula, and index represents the position currently being calculated.

index is specific to Chart calculations.

It is not available in the Formula Editors for:

  • Std Formula Output;

  • Card Formula Output;

  • Gauge Formula Output;

  • Table Formula Output.

Chart Configuration

Available Chart settings depend on the selected Chart type.

Configuration can include:

  • Select Chart

  • Show legend

  • Chart Title

  • Add prefix

  • Add Suffix

  • segment or series colours

  • decimal places

  • Visibility Condition

Some Chart types provide additional controls.

Bar Chart Options

Bar Charts support:

Horizontal bars

Use this option to change the orientation of the bars.

Pie Chart Options

Pie Charts provide additional presentation options including:

  • Donut style

  • Show center total

  • Center label

The default Center label is:

Total

These options allow a Pie Chart to be presented as a traditional Pie or as a Donut-style visualisation with information displayed in its centre.

Line & Area Chart Options

Line and Area Charts provide additional axis configuration including:

  • X-axis Title

  • Y-axis Title

  • Chart X Axis

Use these settings to provide context for the values displayed across the Chart.

Chart Title

A Chart Title is required.

Ekphrastic prevents the Chart from being saved if the Chart Title is empty.

Choose a title that clearly communicates what the Chart represents.

Prefixes, Suffixes & Decimals

Charts support presentation controls including:

  • Prefix

  • Suffix

  • Decimal places

These can be used to provide context for displayed values.

For example, a Prefix or Suffix can indicate:

  • currency;

  • percentage;

  • time;

  • another unit of measurement.

Charts do not provide the dedicated Currency selector available on Standard and Card Formula Outputs.

Use the available Prefix and Suffix controls where units or symbols are required.

Chart Colours

Individual Chart segments or series can have their own colour.

For segment-based Charts, configure:

Chart Segment Color

Line and Area series also provide colour configuration.

Use colours consistently so that users can distinguish categories or series without making the Chart unnecessarily complex.

Chart Validation

Ekphrastic validates the Chart configuration before allowing it to be saved.

A Chart cannot be saved when:

  • Chart Title is empty;

  • a Chart Formula contains an error;

  • required series information is incomplete.

When building multiple series, complete the required Legend and Formula information for the existing series before adding another.

Changing Chart Types

When initially creating a Chart, use Select Chart to choose the required type.

After the Chart has been saved, type changes remain within the same Chart family.

You can change between:

  • Pie Chart;

  • Bar Chart;

  • Polar Area Chart.

You can also change between:

  • Line Chart;

  • Area Chart.

You cannot directly change a saved segment-based Chart such as Pie into a series-based Chart such as Line.

If you need to move between these families, create the appropriate Chart instead.

Conditional Visibility

Charts support Visibility Condition.

This allows a Chart to appear only when the configured condition is met.

If Visibility Condition is enabled, make sure the required source and condition have been configured before saving.

See Conditional Visibility for more information.

Calculate on Hidden

Charts do not provide Calculate on Hidden.

This differs from Standard, Card and Gauge Formula Outputs, where calculation behaviour while hidden can be configured separately.

Attached Resources

Charts do not support Attached Resources.

If supporting evidence or collateral needs to be associated directly with a calculated result, use a supported component such as:

  • Std Formula Output;

  • Card Formula Output;

  • Dynamic Value Text.

See Attached Resources for more information.

Changing the Component Type

Charts cannot be changed into another component type using:

Swap component type

Other Output components also cannot be converted directly into a Chart.

If a different type of Output is required, create the appropriate component instead.

Tables or Charts?

Use a Chart when the visual relationship between values is important.

For example, a Chart can help communicate:

  • how values compare;

  • how a total is distributed;

  • how values change across a sequence;

  • how different series compare.

Use a Table Formula Output when users need to see the exact individual values in a structured grid.

In some ROI Models, both may be appropriate.

For example, a Chart could provide a high-level comparison of projected annual benefits while a Table provides the detailed calculations behind those results.

Tips

  • Choose the Chart type based on the relationship you want to communicate.

  • Give the Chart a clear and descriptive title.

  • Keep Legends concise and easy to understand.

  • Use index when a Formula needs to respond to the position of a data point.

  • Remember that Charts and Tables cannot be used as Formula sources.

  • Use Prefix and Suffix when Chart values require units or symbols.

  • Resolve all Formula and series configuration errors before saving.

  • Avoid adding unnecessary series or segments that make the Chart harder to interpret.

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