Grouping numeric data
You group numeric data by specifying the rows of data that compose the group. The chart builder uses a default interval of 0.5 to create numeric groups. If you change the setting to 20, the first group contains rows with values between 1 and 20, the second group contains rows with values between 21 and 40, and so on. If the chart does not include a value in a group section, that section does not appear in the report. If you group order numbers 150–300 using a value of 20, the first group section that appears in the chart is 141–160.
For example,
Table 16‑2 displays budget data for three cities.
Table 16‑2 Data for a chart that uses category series grouping
Year | City | Budget |
2008 | Los Angeles | 3485398 |
2008 | Chicago | 2783726 |
2008 | New York | 7322564 |
2009 | Los Angeles | 4694820 |
2009 | Chicago | 3196016 |
2009 | New York | 8008278 |
2010 | Los Angeles | 6819951 |
2010 | Chicago | 2569121 |
2010 | New York | 8085742 |
To group data using the Year field, you enable grouping, specify the data type of the field, and define a grouping interval. The data type that you select determines how the chart builder creates the groups as follows:
If Year is a text field, selecting an interval value of 3 creates three groups. The first group includes the first three rows in the table, the second group contains rows four through six, and the third group contains the last three rows.
When you group text values, you must use a regular grouping interval. You cannot create groups of varied sizes or use a field value to create a group. To create sensible groups in the chart, you must arrange the data in your data source before you create the chart. To use more complicated grouping, you should use your query to group data, then you can use those grouped values in the chart.
If Year is a numeric field, selecting an interval value of 3 creates two groups. The first group includes the 1998 rows, because grouping by three from a base value of 1 creates one group that ends with 2008. The second group contains the 2009 and 2010 rows.
After you define how to create the groups, you must select an aggregate function that determines how the chart builder combines the values in each group.