Spiral Plot

The Spiral plot is suitable for comparing Data Values across Categories using a circular shape. It arranges categories along a radial line and encodes data values into circular bars. You can also choose a method of dividing data values into subcategories within a containing category. The examples below emphasize Data Values with a bold font and Categories - with an italic font.

Simple Spiral

In its simplest form, a spiral plot is very similar to a bar plot displayed on a polar coordinate system. For instance, the simple spiral demo shows the Sales Amount per Product Category.

Stacked Spiral

A stacked spiral plot breaks down data values into subcategories by placing corresponding circular subsections next to each other within the containing category. The Stacked Spiral Demo shows the Sales Amount for each sales channel per Product Category.

Percentage Stacked Spiral

A percentage stacked spiral plot combines the stacked spiral plot and the Percentage axis scale. It indicates the contribution of each data values' sub-category to a containing category's total. For instance, the Percentage Stacked Spiral Demo shows the percentage share of the sales channels' Sales Amount per Product Category.

You can configure all these types using the Spiral plot template and its properties that we described in the following sections. The Stacked Spiral and Percentage Stacked Spiral templates are just shortcuts to a specific configuration.

You can use the following demos to explore the plot properties - open a link, toggle the Report explorer, select the Plot - Plot 1 node and use the Properties panel to modify the configuration.

You could also download the report files listed below and open them in the Standalone Report Designer.

Chart Wizard

If you add a chart into a report, set the plot type to Spiral on the first page of the Chart Wizard, and click the Next button, the wizard shows the Spiral Settings page that looks like the following:

Chart Wizard for Spiral Plots

The Data Values section allows you to add one or more Data Values.

The Data Categories section allows you to set the Category Encoding.

The Data Subcategories section allows you to configure the Details Encoding.

Data Values

The Spiral plot is used for comparing items, such as the net sales or the average rainfall. The plot's Values collection determine these items that consist of two properties:

The Value is usually a bound field reference. The Properties Panel displays the Value as the collection, but Spiral plots take the first item only. The Chart Wizard displays Value as Field.
The Aggregate is an optional function, such as Count or Average, that reduces many field values into a single one. If a Bound DataSet contains aggregated values, then you can set this property to None.

For instance, the plot in the Simple Spiral Demo has the Value={SalesAmount}, Aggregate=Sum Data Value.

Spiral plots do not currently support multiple data values. Therefore the Values collection should always contain one item.

Category Encoding

The Category Encoding of a Spiral plot is a set of properties that determine the range of Category Values for which the plot generates circular bars representing those above Data Values.

The Category is usually one or more bound field references. Bound DataSet Records with the same values of these fields fall into the same category. For instance, the Simple Spiral Demo Chart is bound to the Sales DataSet containing several fields per data record including the ProductCategory. The plot's Category list contains the {ProductCategory} reference. Therefore the plot goes through the Sales DataSet and places distinct ProductCategory field values along the vertical radial line.
The Category Sorting configuration determines the order of the category values appearance. For instance, the plot in the Simple Spiral Demo has the following settings to sort the product categories by the sum of sales in ascending order.
- Category Sort Expression = {SalesAmount}
- Category Sorting Aggregate = Sum
- Category Sort Direction = Ascending

The Chart Wizard offers the simplified editor of the Categories Encoding in the Data Categories section:

A single Category Expression displayed as Field is available.
The Sorting configuration of the Category Encoding displays the Sort direction property only. The Sort Expression is automatically set to the Field value.

Details Encoding

The Details Encoding allows you to break down those above Data Values into subcategories within the containing category for more granular comparison.

The Details property of a Spiral plot is the collection of items that define these subcategories. Each item includes several properties:

The Values is usually one or more bound field references. Bound DataSet Records with the same values of these fields fall into the same subcategory. For instance, in the Stacked Spiral Demo the plot's Details value is {SalesChannel}. Consequently, the SalesAmount circular bars break down into multiple subsections corresponding to distinct sales channels.
The Exclude Nulls flag indicates whether DataSet Records with an undefined Details Value should be excluded from the visualization.
The Group property determines how the plot arranges circular bars divided into subsections.
- Stack - a plot places subsections next to each other. You can use this value to configure a Stacked Spiral plot.
- Cluster - subsections are clustered into groups.
- None - equals the default value.
The Sorting configuration determines the order of the subsections' appearance.

The Chart Wizard offers the simplified editor of the Details Encoding in the Data Subcategories section:

A single Details Encoding item is available.
A single Value item displayed as Field is available.
The Group property of the Detail Encoding is displayed as the Break-down method.
The Sorting configuration of the Details Encoding displays the Sort direction property only. The Sort Expression is automatically set to the Field value.

Colors Encoding

The Colors Encoding enables the color legend of the Category Encoding or Details Encoding and includes the Color expression and the optional Color Aggregate function that reduces many Color values into a single one.

Suppose the Details Encoding is empty. In that case, a Spiral plot calculates distinct Color Encoding results for the categories produced by the Category Encoding, convert them to the background color of the corresponding circular bars, and displays the match in the legend.

Otherwise, the plot calculates distinct Color Encoding results for the subcategories produced by the Details Encoding, converts them to the background color of the corresponding subsections, and displays the match in the legend.

In both cases, plots pick up colors from the Chart Palette.

For instance, the colors encoding in the Stacked Spiral Demo is set to the {SalesChannel} expression. Consequently, the report output shows the legend that matches Sales Channels with corresponding bar subsections background.

In most cases, you will use the same configuration for both Details Encoding and Colors Encoding to enable a visual map of data values breakdown.

Note: The Color property is the collection, but the Spiral plot takes the first item only.

Spiral look-and-feel

The following properties allow you to fine-tune the outfit of geometrical shapes that form Spiral plots. You can see their effect in action by modifying the configuration of spiral plot demos.

The Opacity is a Number in percentage that determines the opacity of circular bars. 100% means they are opaque, and 0% means that they are completely transparent.

The Inner Radius is a number in the percentage of the outer radius that defines the size of a hole in the center of the plot.

The Start Angle is a number in arcdegree that defines the rotation of the plot clockwise. Full rotation is 360 degrees. In all the spiral plot demos, this property is set to 90.

The Sweep is a number in arcdegree from 0 to 360 that determines the arc length occupied by the plot. In all the spiral plot demos, this property is set to 270.

The Clipping Mode indicates the manner that the plot area draws a plot:

Fit value means that the plot area should use all the available space to fit the plot
Clip value means that the plot area cuts off the plot on the edge of its right or bottom padding
None value equals to Fit

The line properties in the Style section determine the appearance of circular bars borders.

The color expression in the Background section sets the fill color of circular bars and overwrites the Color Encoding described earlier.

Customizing Tooltips and Labels

The Text Encoding collection offers a way to configure spiral plots to display customized labels and tooltips on the circular bars. Each item within this collection has the following properties:

Values: This is an expression that can reference the values of the bound fields.
Aggregate: This optional function, such as Count or Average, can condense multiple field values into a single value, evaluated within the current detail or category context.
Template Key: A string used within the Labels or Tooltip template to represent the text encoding item.
Target: This property specifies whether the text encoding item is meant for the plot's labels or tooltips.

Adding items to the Text Encoding collection allows automatic display of configured values in Labels or Tooltips, based on the Target value of each item. To further customize the text of the labels and tooltips, you can employ the Tooltip Template and Label Text Template expressions.

Apart from Text Encoding items referenced by their keys, you can utilize the following pre-defined values:

{valueField.name}: Represents the field name bound to a Data Value.
{valueField.value}: Represents the current Data Value within the containing Category or Details.
{PercentageDetail}: Represents the percentage share of the current Data Value among all values within the same Details.
{PercentageCategory}: Represents the percentage share of the current Data Value among all values within the same Category.
{categoryField.name}: Represents the field name bound to the Category Encoding.
{categoryField.value}: Represents the current Category Encoding value.
{detailFields.name}: Represents the field name bound to the Details Encoding.
{detailFields.value}: Represents the current Details Encoding value.
{colorField.name}: Represents the field name bound to the Color Encoding.
{colorField.value}: Represents the current Color Encoding value.

These values can be combined and formatted using the interpolation syntax and supported format strings that are also used for the TextBox Report Item.

For example, the plot in the Simple Spiral Demo uses an advanced tooltip configuration:

The Text Encoding contains the SalesQuantity element that displays the number of sold items:
- Aggregate = Sum
- Value = {SalesQuantity}
- Target = Tooltip
- TemplateKey = SalesQuantity
The Tooltip Template is configured with the following expression:

{categoryField.value}
Quantity: {SalesQuantity}
Amount: {valueField.value:C2}

Labels Appearance

A subset of text properties in the Label Text section and the line properties in the Label Border section allow you to set up the corresponding visual parameters of the plot labels.

The Label Position and an optional Offset in pixels determine the location of labels relative to a parent circular bar:

Inside - on the edge
Outside - outside
Center - inside, on the center
Auto - equals to Outside

The Overlapping Labels property indicates the handling of overlapping labels. Possible values are:

Auto - hides some labels to prevent the overlapping
Show - shows all labels even if the overlapping persists

The line properties in the Label Line section allows you to add the connecting lines between labels and their parent circular bars. The Label Line Position determines the starting point of the line relative to the sector:

Auto - on the edge
Center - on the center

Dynamic Rules

The Rules configuration allows you to create if this then that rules based on one or more data conditions to apply to the plot appearance. A condition is an expression that may refer to one of the following values:

Chart!CurrentData - the current Data Value
Chart!PreviousData - the previous Data Value
Chart!NextData - the next Data Value
Chart!CurrentCategory - the current Category Encoding value
Chart!PreviousCategory - the previous Category Encoding value
Chart!NextCategory - the next Category Encoding value
Chart!CurrentDetail - the current Details Encoding value
Chart!PreviousDetail - the previous Details Encoding value
Chart!NextDetail - the next Details Encoding value

A condition expression can also include references to report parameters and standard operators. The easiest way to build a condition is to use the expression editor that you can open by click on the box on the right side of the Condition property.

The following visual properties of a Spiral plot can be applied when a condition is met:

The background color of a circular bar
The color of the circular bar border
The width of the circular bar border
The style of the circular bar border
The tooltip and label template

For instance, you can set the following rules for the plot in the Simple Spiral Plot Demo to apply the specified background color to the curcular bar when the Category is Computers:

As a result, the output of the chart will be like this:

Action

This properties determine the Interactive Action when a report reader clicks inside a circular bar. You can use bound field references to pass parameters in a drill-through report or configure a dynamic bookmark or URL. The field value is evaluated in the scope of the current detail. Visit the Drill-Through Reports Walkthrough for more information. It explains how to set up the drill-through column plot, but the same technique applies to a spiral plot.