# No Value Specification

ChartDirector Ver 5.0 (PHP Edition)

No Value Specification

To draw charts, you need to supply data. In ChartDirector, data are supplied as an array of numbers.
In many cases, a data point will be missing. For example, suppose you are drawing a line chart with one data point per hour. It is possible that due to various reasons, some data points could be missing. However, if you are using an enumerated x-axis (see Axis.setLabels), you cannot not simply remove that point, otherwise the remaining points will all be shifted.
To address this kind of issues, ChartDirector supports a special constant called NoValue, which is equal to 1.7E+308. When ChartDirector sees that a data point is NoValue, it will jump over that point.
In a line chart, if a data point is NoValue, ChartDirector will jump over to the next data point. ChartDirector can use an alternative line color when jumping over a NoValue point to visually reflect that there is a missing point. The default alternative line color is Transparent, which means the NoValue point will result in a discontinuous line. You may use LineLayer.setGapColor to change it to other colors, such as using SameAsMainColor (same color as the normal line) or a dash line color.

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