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Working with Chart Axes (Report Builder 1.0)

Typically, charts have two axes which are used to categorize and measure data. An axis is a line bordering the chart plot area used as a frame of reference for measurement. The y-axis is usually the vertical axis and displays data. The x-axis is usually the horizontal axis and displays categories. For example, a sales-to-date report by region would probably have the dollar amounts displayed along the y-axis and the name of each region along the x-axis. Pie and doughnut charts do not have axes.

The labels along the axes are based on the field names and the data contained within your data source. They can be formatted but they cannot be changed.

Gridlines

Gridlines are regularly spaced horizontal and vertical lines in a chart that make it easier to view and evaluate data. There are two types of gridlines: major and minor. When added to a chart, major gridlines run along the axis at major interval values. When added to a chart, minor gridlines run along the axis at each interval. For example, suppose the values along the y-axis are between 0 and 50. The major gridlines are displayed at the 10, 20, 30, 40, and 50 values. If minor gridlines are added, they are displayed at each value between 0 and 50.

Tick Marks

Tick marks extend from the gridlines on an axis across the plot area. Tick marks are small lines of measurement, similar to divisions on a ruler, that intersect an axis. You can adjust the interval between tick marks, their location in relation to the axis gridline, line style and color.

Numbers and Dates

Dates and numbers are displayed in the order specified by the data source. For example, if dates are ordered chronologically, dates in the chart appear in order by default. You can change the order by grouping and sorting your data.

When you create a chart using fields that contain numbers or dates, and they appear on the x-axis in the chart, you can specify that the x-axis be treated as a numeric or time-scale values axis, also referred to as scalar mode. In scalar mode, only one grouping can exist on the x-axis. Scalar mode can be applied to line, column, bar, or area charts.

In scalar mode, numbers are displayed in numeric order, from lowest to highest. If you sort the numbers so that they appear from highest to lowest, the y-axis is automatically moved from the left side of the chart to the right side of the chart.

Dates

In scalar mode, dates are displayed in chronological order at specific intervals. Report Builder initially sets the time-scale intervals according to the smallest difference between any two dates in the data. For example, if you have data for sales totals where the smallest difference between dates is three days, Report Builder presets the time-scale interval to days.

When using dates in scalar mode, you can still adjust the time-scale. By default, the date before the first date in the data is used as the y-axis. For example, if your data returns dates between 1/1/2003 and 1/31/2003, the y-axis value is 12/31/2003. The last date in the data series is the last value on the x-axis, unless you select the Side margins option, which extends the last value displayed by one day. For example, if the last date with data is 1/30/2003, this is the last value displayed along the x-axis. Select the Side margins option and the x-axis is extended to 1/31/2003.

Report Builder charts recognize dates as sequential numbers which are called serial values. By default, January 1, 1900 is serial number 1, and January 1, 2008 is serial number 39,448 because it is 39,448 days after January 1, 1900. Chart dates are handled as decimal fractions because time is considered a portion of a day. When specifying gridline values for your chart in scalar mode, enter 1 in the Show major gridlines Interval box to display the intervals as days and enter .5 to display time intervals as 12 hour periods. For other date intervals, divide by 1/24 and convert the fraction to a decimal, then enter the decimal in the Interval box.

Scale

Scale is used to help put the data in perspective. You can specify the scale displayed on both axes to help make your chart more readable. For example, suppose your chart displays values between $20 and $120 along the y-axis. To make your chart easier to read, you might want to adjust the scale to display values between 0 and 150. By default, the minimum scale value is zero (0). If no maximum value is specified, the highest value returned in the data is used as the maximum value for the scale.