Charts

Charts display data much the same way as grids. Grids are composed of two dimensions, rows and columns, which are translated one-to-one with chart series and categories. This one-to-one relationship extends to all pieces of displayed information: row/column headers in the grid become series/category text in the chart; rows/columns of data in the grid become series/categories in the chart; a grid cell, which is the intersection of a row and column, is mapped directly to a chart data point, which is the intersection of a series and category. You can think of a chart containing data like a grid --as an array or table. The difference is seen only in the display: the grid shows numbers in spreadsheet style, the chart presents those numbers as graphics against a graded scale.

Series are collections of instances of data of the same type, identified by color. Series are identified in the legend by a color and a text string that maps to the member name. Categories are the groupings containing one piece of data from each and every series, a categorical cross section of the series. In bar, line, area, combo, and high-low charts, the categories appear along the X axis, labeled with a text string that is mapped from the member name. In a pie chart, the category is the pie, it contains a slice (color) from every series.

When designing a chart, you need to consider how the size of all the chart elements will interact within a static size area for the chart. The chart elements (plot, legend, title, axes, and so on) are laid out with respect to each other and the provided size and shape of the object. The amount of data and text chosen may not fit cleanly in a particular size window. If, for instance, there are a large number of chart series, the legend size is bigger to accommodate those series and there is less room for the chart plot. A large number of chart divisions or long text strings for the names of series and divisions also impacts the size and readability of the chart plot.

When creating a chart, you must manage the amount of text and data in a chart with respect to the size of the chart object. If a chart becomes unreadable from too much information in too little an area, you can use any of the these steps to help.

• Enlarge the chart window.
• Decrease the amount of data (in other words, the number of members) in the chart.
• Turn off the legend and/or title.
• Select a scale factor.
• Decrease font sizes.
• Use one of several axis label Fit options.