Using Rulers and Reference Lines
Rulers provide the capability to add reference lines and customize the markers used on the metric axis.
Use reference lines to mark limits, thresholds, critical values, and so on. Reference lines can mark both positive and negative values on an axis and multiple lines can be added in a chart.
Rulers also let you change the (metric) axis range in a chart along with the markers along the axis. Customizing this range may help you focus your data exploration to specific data points. You can set min and max values for your axis, define the steps, enable gridlines, and use a logarithmic scale.
Rulers functionality is available only for bar charts and line charts.
Select Rulers on the chart drop-down menu. The Rulers sidebar displays. The sidebar consists of two sections: the (metric) axis range and reference lines.
Configuring the Axis Range Settings
The axis range displays the minimum and maximum values for the metric used in the chart. You can use Rulers to configure the default values for Min, Max, and Step. When the Rulers sidebar is initially opened, these settings are set to Auto. For example, in Figure 1, the Volume metric has a Min value of 0, while the Max value is 20.
To customize this range, clear the Auto checkbox and then enter your custom value in the fields. Customizing the axis in this way can create a view into your data that drills into specific information, explore anomalies, and otherwise explore more relevant information.
You can further this exploration by specifying the Step for the tick marks along the axis. This step can be specified down to the tenth place, or one decimal point. For example, you can step the tick marks by .5 tenths.
If have specified the step, which can not be displayed on the axis, the default minimal step value is applied.
Grid lines provide a visual cue between data elements and metric ranges in the chart. They are displayed as light gray lines on the canvas and from each axis:
- Extend from the tick marks on the metric axis.
- Go through the center of the data element on the attribute axis.
Grid lines may help you to analyze and compare the data elements in your chart. To enable grid lines, select the Gridlines checkbox for the corresponding axis.
Log Scale Function
The Log Scale function changes the metric axis based on orders of magnitude of the selected metric. A log scale is nonlinear and best utilized when there is a large range of quantities. Keep in mind that log scales can only be used for positive values. Negative values are displayed as ‘1’ in the metric axis. In addition, when this option is selected, the Auto option is enabled for Min, Max, and Step.
The scale is built for whole the data range. Select the Log scale checkbox to enable.
When you save or export your chart, the settings configured in Rulers are saved or exported respectively.
Creating and Using Reference Lines
To add a reference line to your chart, perform the following steps:
In the Reference Lines section, click Add Line. The reference line is displayed on your chart.
Fill in the following fields as needed:
- Position - By default, the reference line is added to the middle of the visible axis. You can specify a different position on the axis by either entering a specific number value or using the slider. The reference line changes its position depending on your input.
- Title - Specify the name for the line. The default name of the line is Reference line #.
- Color - Select the desired color for the line.
- Width - Specify the line’s thickness: enter a specific value or use the slider.
- Line type - Select from the following types: Solid, Dashed, or Dotted.
You can add multiple reference lines in a chart.
Modifying a Reference Line
You can modify the reference lines from the Rulers sidebar and directly on the chart.
To edit the line on your chart, click on it to open the Edit Reference Line dialog. It contains the same options as the Rulers sidebar. All the changes are applied automatically.
Deleting a Reference Line
To delete a reference line, you can either find it in the Rulers sidebar or open the Edit Reference Line dialog on your chart and click Delete.