ing data values to a visual color range." width="45%" />
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FIGURE 2.2: Mapping data values to a visual color range.
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<p>Since these arguments map data values to a visual range by default, you will obtain unexpected results if you try to specify the visual range directly, as in the top portion of Figure <a href="overview.html#fig:intro-range">2.3</a>. If you want to specify the visual range directly, use the <code>I()</code> function to declare this value to be taken ‘AsIs’, 