User Help > Displaying Item Data Graphically > Creating a Chart > Item Fields Chart: Add Expression or Edit Expression Dialog Box
 
Item Fields Chart: Add Expression or Edit Expression Dialog Box
The Add Expression dialog box allows you to create a computed expression for an item fields chart. The Edit Expression dialog box allows you to edit a computed expression for such a chart.
1. In the Field Name/Expression field, create a computed expression that incorporates one or more numeric fields in the items returned by the specified query. For example, if your chart currently displays a list of Project items, typing: ("Actual Budget" - "Estimated Budget")calculates the difference between the Actual Budget and Estimated Budget fields for each Project item and displays the values in the chart. You can also manually insert fields into your expression by selecting a field from the field list and clicking Insert Field. For more information on creating computed expressions, see What are Computed Expressions?.
Depending on the number of computed expressions you create, certain graph styles become available. For example, if you include two computed expressions, the XY (scatter) graph style is available. If you include three computed expressions, the bubble style graph is available. For more information on selecting graph styles, see To specify a graph for a chart.
2. In the Expression Label field, type a name for the computed expression label as you want it to display in the chart. For example, if you have a computed expression that calculates the difference between theActual Budget andEstimated Budget fields for each Project item, an appropriate label might be Over/Under Budget. If you do not define a label, the computed expression displays, for example, ("Actual Budget" - "Estimated Budget").
3. In the Display Pattern field, select or type a display pattern for the value of the computed expression.
4. In the Axis Label field, do one of the following:
If your chart contains one computed expression, type a name for the numeric axis as you want it to display in the chart.
If your chart contains multiple computed expressions and you want to specify the same axis label for all computed expressions, type a name for the numeric axis as you want it to display in the chart, or select an existing axis label from list.
If your chart contains multiple computed expressions and you want to specify an axis label for each computed expression, type a name for the numeric axis as you want it to display in the chart.
5. To add the computed expression to the chart, click OK.