Changing the Axis and Scale Settings

There are several options for modifying axes and scales.

How to change axis and scale settings

1. Select any part of the axis (for example, the axis label or tick labels).
2. Use the Scale, Major Ticks, and Minor Ticks tabs on the properties palette to change the axis and scale settings.

Scale tab

Note: The Scale tab does not appear for graphs where the data is pre-aggregated (for example, histograms).

Type. Specifies whether the scale is linear or transformed. Scale transformations help you understand the data or make assumptions necessary for statistical inference. On scatterplots, you might use a transformed scale if the relationship between the independent and dependent variables or fields is nonlinear. Scale transformations can also be used to make a skewed histogram more symmetric so that it resembles a normal distribution. Note that you are transforming only the scale on which the data are displayed; you are not transforming the actual data.

• linear. Specifies a linear, untransformed scale.
• log. Specifies a base-10 log transformed scale. To accommodate zero and negative values, this transformation uses a modified version of the log function. This "safe log" function is defined as sign(x) * log(1 + abs(x)). So safeLog(-99) equals:

  sign(-99) * log(1 + abs(-99)) = -1 * log(1 + 99) = -1 * 2 = -2

• power. Specifies a power transformed scale, using an exponent of 0.5. To accommodate negative values, this transformation uses a modified version of the power function. This "safe power" function is defined as sign(x) * pow(abs(x), 0.5). So safePower(-100) equals:

  sign(-100) * pow(abs(-100), 0.5) = -1* pow(100, 0.5) = -1 * 10 = -10

Min/Max/Nice Low/Nice High. Specifies the range for the scale. Selecting Nice Low and Nice High allows the application to select an appropriate scale based on the data. The minimum and maximum are "nice" because they are typically whole values greater or less than the maximum and minimum data values. For example, if the data range from 4 to 92, a nice low and high for scale may be 0 and 100 rather than the actual data minimum and maximum. Be careful that you don't set a range that is too small and hides important items. Also note that you cannot set an explicit minimum and maximum if the Include zero option is selected.

Low Margin/High Margin. Create margins at the low and/or high end of the axis. The margin appears perpendicular to the selected axis. The unit is pixels unless you indicate a different unit (such as cm or in). For example, if you set the High Margin to 5 for the vertical axis, a horizontal margin of 5 px runs along the top of the data frame.

Reverse. Specifies whether the scale is reversed.

Include zero. Indicates that the scale should include 0. This option is commonly used for bar charts to ensure the bars begin at 0, rather than a value near the height of the smallest bar. If this option is selected, Min and Max are disabled because you cannot set a custom minimum and maximum for the scale range.

Major Ticks/Minor Ticks Tabs

Ticks or tick marks are the lines that appear on an axis. These indicate values at specific intervals or categories. Major ticks are the tick marks with labels. These are also longer than other tick marks. Minor ticks are tick marks that appear between the major tick marks. Some options are specific to the tick type, but most options are available for major and minor ticks.

Show ticks. Specifies whether major or minor ticks are displayed on a graph.

Show gridlines. Specifies whether gridlines are displayed at the major or minor ticks. Gridlines are lines that cross a whole graph from axis to axis.

Position. Specifies the position of the tick marks relative to the axis.

Length. Specifies the length of the tick marks. The unit is pixels unless you indicate a different unit (such as cm or in).

Base. Applies only to major ticks. Specifies the value at which the first major tick appears.

Delta. Applies only to major ticks. Specifies the difference between major ticks. That is, major ticks will appear at every nth value, where n is the delta value.

Divisions. Applies only to minor ticks. Specifies the number of minor tick divisions between major ticks. The number of minor ticks is one less than the number of divisions. For example, assume that there are major ticks at 0 and 100. If you enter 2 as the number of minor tick divisions, there will be one minor tick at 50, dividing the 0–100 range and creating two divisions.