Design Guide 5.1.2 > Scales and Grids

Value Scales

Value scales are used to indicate the numeric values of your graph's data item. All graphs, except for Pie graphs, have at least one value scale. X-Y graphs have two value scales—one for both the x and y axis. Likewise, Line Bar Combo graphs and graphs with dual y scales have two value scales.

In most cases, the value scale appears on the left or right side of a graph. For X-Y graphs, there will also be a value scale (the x-scale) at the bottom of the graph. For Horizontal Bar graphs, the value scale is at the bottom instead of the side.

There are a number of customization features for value scales

Adjusting the Range of a Value Scale

The range of your scale is, by definition, the set of values the scale encompasses. This is defined by a minimum (low) value, which is the lowest horizontal line, and a maximum (high) value, which is the highest horizontal line. For example, in the graph below, the range is from 405 to 480.

By default, PopChart+OptiMap automatically computes the range of your value scales so that they include all of the data items in your graph. This means that you usually don't have to worry about defining the range of your scale.

For example, if your data items were 2, 6, 9, and 3, PopChart+OptiMap would automatically determine the range of your scale to be 0 to 10. On the other hand, if the values were 289, 390, and 457, it would automatically determine the range to be 0 to 500. Note that it tries to use nice, even numbers when it creates the ranges. Thus the latter range is 0 to 500 instead of 0 to 457.

Of course, you can always override this automatic scaling and specify the ranges yourself. But even with automatic scaling, you still have several advanced formatting options, such as whether or not the scale begins with zero. Options for both automatic and manual scaling are discussed below:

Setting the Base of the Scale to Zero

By default, the base (bottom line) of most value scales is zero. However, in the image at the top of this section, the base of the scale is 405. This is because we turned off a setting that instruct PopChart+OptiMap to set the base of the scale to zero.

Turning off this behavior can be useful whenever you data values are all very close to each other, but not very close to zero. For example, in the image at the top of this section, if the base of this scale were zero, we would hardly be able to differentiate between the three lines because they would all be so close together. Be aware, however, that this can deceive a viewer of the graph, as most viewers assume that the base of a graph is inherently zero.

To set (or unset) the base of a scale to zero

These instructions only apply to automatically scaled graphs, as you must explicitly set the base of a manually scaled graph.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.



  3. In the Scale dialog pane, make sure that the setting for Set Scale Values is Automatically.
  4. Check (or uncheck) the Set base of scale to zero box.
  5. Click Apply or OK to save your settings.

Controlling the Amount of "White Space"

You've probably noticed that the range of your scale is somewhat larger than the highest data value in the graph. This is partly because PopChart+OptiMap puts "white space" between your highest data value and the top of the graph, and partly because PopChart+OptiMap likes to use round numbers (50, as opposed to 47) for the scale.

You can control the amount of white space above your highest data item. If you have selected not to set the base of the scale to zero, you can also specify the amount of white space below the lowest data item.

To change the amount of white space in the scale

These instructions only apply to automatically scaled graphs, as you must explicitly set the size of a manually scaled graph.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. In the Scale dialog pane, make sure that the setting for Set Scale Values is Automatically.
  4. In the Percent over max value box, enter the desired percentage of white space above the highest data item.

    5. White space is expressed in terms of the percentage of space between the base of the graph and the highest data item. So, for example, in a graph where the highest data item is 50, and the base is zero, setting this value to 10 percent would mean that the white space would add 5 to the scale.

    Note that after adding white space, PopChart+OptiMap will still round your scale to an even number, so this number may not exactly reflect the white space you end up seeing.

  5. (Optional) If the base of your scale is not zero, and you want to adjust the white space below the graph, enter the desired percentage of white space in the Percent under min value box.
  6. Click Apply or OK to save your settings.

Manual Scaling

If you do not want have PopChart+OptiMap automatically configure your range, you can specify the minimum and maximum values of your scale manually. The disadvantage of this is that it makes your graph less flexible—if the data is outside the specified range, it will be cut off and invisible to a viewer.

However, there are many circumstances where it is desirable to manually control the range. For example, suppose you are graphing student test scores. On one test, performance is particularly bad, and the highest score is 72. Under automatic scaling, your range would probably be from 0 to 75, which would create a somewhat deceiving graph. Instead of relying on automatic scaling, you would probably want to manually set the range to be from 0 to 100.

To manually set the range
  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. In the Scale dialog pane, change the setting for Set Scale Values to Manually.

    4. The options below this setting will change as you do this.



  4. In the Minimum Value box, enter the low value for the scale range.
  5. In the Maximum Value box, enter the high value for the scale range.
  6. Click Apply or OK to save your settings.

Controlling the Number of Increments in the Scale

PopChart+OptiMap divides your scale into a certain number of increments, each of equal values (except in logarithmic scales). Between each major increment, there is a scale label, as well as a tick mark and a grid line. There are also minor increments that divide up the space inside of each increment.

For example, a scale with a range of 0 to 500 might be divided into five major increments, meaning there would be six labels: 0, 100, 200, 300, 400, and 500. Between each label would be a minor tick mark, indicating 50, 150, 250, and so on.

To specify the number of labels in the scale

You can control the number of labels, grid lines, and/or tick marks in a value scale by adjusting the number of increments in the scale.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon where the scale you want to change is located.

  3. Go to the Scale dialog pane.
  4. (For automatic scales) Enter the maximum number of increments you want in the Maximum Major Ticks box.

    5. This is the maximum number of major tick marks (which corresponds to the number of scale labels and major grid lines) that will appear in the graph. There will be no more than this number of ticks. However, there may be less, since PopChart+OptiMap likes to round the labels to keep them from being uneven values. For example, if trying to do seven labels would end up creating labels like 16.67, 33.33, and so on, PopChart+OptiMap might go down to six labels so that it could create labels like 20, 40, and so on.

  5. (For manual scales) In the Number of Major Ticks box, enter the number of increments you want to see.
  6. (Optional) You can also control the number of minor tick marks between each label by entering a number in the Number of Minor Ticks box.
  7. Click Apply or OK to save your settings.

Configuring Value Scale Labels

Next to each major tick mark or gridline in a value scale you will find a scale label. This label is simply a number that indicates the value of the scale at the indicated tick mark or gridline.

The number of labels in a value scale is dictated by the number of major increments in that scale. See the previous topic, "Controlling the Number of Increments in the Scale," for information about adjusting the number of increments in your scale.

You can customize the following aspects of your scale labels.

Enabling or Disabling Labels

In some situations, you may find it desirable to hide labels in a value scale. Or, you may need to re-enable labels that have already been hidden.

To hide (or show) scale labels
  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.

    4. The following dialog will appear:

    :

  4. Uncheck the Display Scale Labels box to hide your labels. Or check it to re-enable your labels.
  5. Click Apply or OK to save your settings.

Changing the Label Font

You can change the font style and color for your scale labels.

To change the scale label font

  1. Select the graph.
  2. Select Properties > Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Font tab.

    4. The following dialog will appear:



  4. Select the desired font.
  5. Specify the desired font style.
  6. Specify the desired color for your text by clicking on the Text Color button and selecting a new color in the Color Properties dialog.
  7. Click Apply or OK to save your settings.

Rotating Labels

You can also rotate your value scale labels. You can use this effect for aesthetic appeal, or to decrease the space required to display your scale labels. The labels in the value scale (left-side) of the graph below are rotated.

To rotate your value scale labels
  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Check the Rotate Labels box.
  5. Select the number of degrees you want to rotate your labels from the accompanying pull-down menu.

    6. You can choose 15, 30, 45 degrees, both clockwise (negative) and counter-clockwise (positive).

  6. Click Apply or OK to save your settings.

Numeric Formats and Abbreviations

In graphs with large numbers, your scale labels may grow to undesirable sizes. To compensate for this, you can change the way your labels are displayed, so that they use an abbreviation of some sort. For example, 1,250,000, might be abbreviated as 1.25m.

Or, to properly represent your values on the scale, you may need to give PopChart+OptiMap some information about the nature of your data. For example, if your numeric values are actually percentages (in other words, a value of 40 represents 40%), you should tell PopChart+OptiMap that your values are percentages so that it can properly display them on the scale.

The following instructions will help you use abbreviations with or adjust the numeric format of scale labels.

To abbreviate your scale labels
  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Under Abbreviations, select Auto Abbreviate.

    5. This will automatically abbreviate your labels. Under this setting, PopChart+OptiMap will abbreviate any label that has more than three non-decimal digits. So, for example, 900 would not be abbreviated, while 1,200 would be abbreviated as 1.2k.

    You can customize the character(s) used for abbreviations. For example, if you would rather use an upper-case K instead of a lower-case k, you can do so. For more information, refer to "To define number abbreviations".

    If PopChart+OptiMap's auto-abbreviate algorithm does not work for you, you can manually specify the abbreviations for your data by selecting Manually Abbreviate instead. The Display Value As pull-down menu allows you to specify to what value the numbers in the label will be relative. The Show Abbreviation check box allows you to select whether or not to show the abbreviation character(s) for the display scheme you have chosen.

  5. Click Apply or OK to save your settings.
To display your labels with a currency symbol

By telling PopChart+OptiMap that your data values represent currency, you can display a currency symbol before or after your scale labels.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Under Numeric Format, select Currency from the Display Label As pull-down menu.

    5. You can define what currency symbol will be displayed in the Project Properties dialog, as discussed in "To define the currency symbol".

  5. Click Apply or OK to save your settings.
To display your labels as percentages

If your values represent percentages rather than whole-numbers, you can instruct PopChart+OptiMap to treat them as percentages. PopChart+OptiMap will append a percentage symbol to your scale labels.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Under Numeric Format, select Percentage from the Display Label As pull-down menu.

    5. You can define what currency symbol will be displayed using the Project Properties dialog, as discussed in "To define the currency symbol".

  5. Click Apply or OK to save your settings.
To change decimal display options

By default, your scale labels will be extended to a maximum number of two decimal places before they are rounded (e.g. 1.9875 is displayed as 1.99). You can change this behavior so that labels are extended to more or less places. You can also select to always show the maximum number of decimal places, even when their values are 0.

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Under Numeric Format, enter the maximum number of decimal places in the Maximum Decimal Places box.
  5. If you always want to show this number of decimal places, check the Always Show Max Decimal Places box.

    6. When checked, numbers that usually wouldn't be extended to decimal places (such as 4), will be extended to those places (e.g. 4 appears as 4.00). This is useful when, for instance, your values represent currency, and you want a label to read $4.50 instead of $4.5).

  6. Click Apply or OK to save your settings.
To change negative value display options

If a scale label is negative, the label will by default be preceded by a minus sign -. Alternatively, it can be placed in parenthesis ( ), or displayed as an absolute value (no negative value indicator).

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon the location of the scale you want to change.

  3. Select the Label tab.
  4. Under Numeric Format, select the appropriate display options from the Negative Values pull-down menu.
  5. Click Apply or OK to save your settings.

Logarithmic Scales

You can turn any value scale into a logarithmic scale. In most scales, the increment between each tick mark is of equal value (e.g. 10, 20, 30, 40, and so on). In logarithmic scales, however, the increment between each tick mark increases by a logarithmic factor from start to finish (e.g. 10, 100, 1000, 10000, and so on).

This allows you to better graph data sets where the majority of the data values are extremely low, but a few data values may be unpredictably high. For example, if the graph below were not logarithmic, the majority of its data points would be squashed together in the lower 1/16th of the graph.

To enable logarithmic scales

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale, Right Scale, or Bottom Scale) will depend upon where the scale you want to change is located.

  3. In the Scale dialog pane, check the Use Logarithmic Scales check box.
  4. Click Apply or OK to save your settings.

Specifying the Position of a Value Scale

By default, if a value scale is on the vertical axis of a graph, it will be placed on the left side of that graph. However, you can place it on the right side of the graph instead.

To change which side of a graph the scale is on

  1. Select the graph.
  2. Select Properties > Left/Right Scale Properties.

    3. The exact title of the dialog (Left Scale or Right Scale) will depend upon which side of the graph the scale currently resides on.

  3. Select the Scale tab.

    4. The following dialog appears:



  4. From the Position Scale option, select either On left or On right.

    5. The following figure shows a graph under each setting.

    .

  5. Click Apply or OK to save your settings.

Working with Dual Value Scales in Line-bar Combo Graphs

When using a Line-Bar Combo graph, you will have a separate value scale on each side of the graph. Under the default scale configuration, the value scale for the line data series is placed on the left side, while the scale for the bar data series is placed on the right side.

You can edit both the left and the right scale independently of each other. The formatting options will be the same.

.
To synchronize the Line and Bar Scales

One of the greatest advantages of a Line Bar Combo graph is that the scales operate independently of each other, allowing you to graph two disparate data sets on the same graph. This means that the left scale might go from 0 to 500, while the right scale might go from 0 to 10.

However, in some cases you may want to synchronize the scales (make it so both scales go from 0 to 500).

  1. Select the graph.
  2. Select Properties > Right Scale Properties.

    3. If you have already switched the position of the line and bar scales, you should access the Left Scale Properties dialog instead.

  3. Select Sync line and bar scales.

    4. This setting will synchronize the left and right scale.

    For example, suppose the data values for the line data series in the graph range from 0 to 100, with Maximum Major Increments set to 5. The resulting line scale displays these scale labels: 0, 25, 50, 75, and 100. Meanwhile, the data values for the bar data series in the graph range from -20 to 90, and the resulting scale labels are -20, 7.5, 35, 62.5, and 90.

    When Sync line and bar scales is selected, a new scale is created to encompass the range of all data values in the graph. In this example, the resulting scale has these scale labels: -50, 0, 50, and 100. This scale will be the same on both sides of the graph. For additional information on setting scale values, see Adjusting the Range of a Value Scale.

  4. (Optional) If you no longer want to display the second scale, you can hide it by checking Hide scale.

    5. This setting will hide the scale on the right side of the graph. It is only available when the Sync line and bar scales setting is selected.

  5. Click Apply or OK to save your settings.
To switch Line-Bar Combo scale positions

You can swap the line scale with the bar scale (so the line scale is on the right and the bar scale is on the left).

  1. Select the graph.
  2. Select Properties > Left Scale Properties.

    3. If you have already switched the position of the line and bar scales, you should access the Right Scale Properties dialog instead.

  3. Select the Scale tab.

    4. The following dialog appears



  4. From the Position Scale option, select one of the following:
  5. Line scale left, bar scale right
  6. Bar scale left, line scale right
  7. Click Apply or OK to save your settings.
 CORDA
Design Guide 5.1.2 > Scales and Grids
Copyright © 1996-2003 CORDA Technologies Inc.™ - PopChart™, OptiMap™,   All Rights Reserved.