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  28  <H3><A NAME="7_1_5">7.1.5 Adding a legend to the graph</A></H3>
  29  <P> With more than one plot on the same graph it is necessary to somehow
  30   indicate which plot is which. This is normally done by adding a legend
  31   to the graph.</P>
  32  <P> You will see that each plot type has a 'SetLegend()' method which is
  33   used to name that plot in the legend. SO to name the two plots in the
  34   example we have been working with so far we need to add the lines<DIV class="phpscript">
  35  <CODE><FONT color="#000000"> <FONT color="#0000BB">&nbsp;$lineplot</FONT><FONT
  36  color="#007700">-&gt;</FONT><FONT color="#0000BB">SetLegend</FONT><FONT color="#007700">
  37  (</FONT><FONT color="#DD0000">&quot;Plot&nbsp;1&quot;</FONT><FONT color="#007700">);
  38  <BR></FONT><FONT color="#0000BB">$lineplot2</FONT><FONT color="#007700">
  39  -&gt;</FONT><FONT color="#0000BB">SetLegend</FONT><FONT color="#007700">(</FONT><FONT
  40  color="#DD0000">&quot;Plot&nbsp;2&quot;</FONT><FONT color="#007700">);</FONT><FONT color="#0000BB">
  41  </FONT></FONT></CODE></DIV></P>
  42  <P> to the previous code. The resulting graph is shown below<DIV class="example">
  43  <BR> <A href="exframes/frame_example5.1.html" target="blank"><IMG border="0"
  44  HEIGHT="200"       src="img/img/img/img/img/img/example5.1.png" WIDTH="300"></A>
  45  <BR><B>Figure 12:</B> Adding a legend to the graph <A href="exframes/frame_example5.1.html"
  46  target="blank">[src]</A>&nbsp;
  47  <P></P>
  48  </DIV></P>
  49  <P> As you can see the legend gets automatically sized depending on how
  50   many plots there are that have legend texts to display. By default it
  51   is placed with it's top right corner close to the upper right edge of
  52   the image. Depending on the image you might want to adjust this or you
  53   might want to add a larger margin which is big enough to accompany the
  54   legend. Let's do both.</P>
  55  <P> First we increase the right margin and then we place the legend so
  56   that it is roughly centered. We will also enlarge the overall image so
  57   the plot area doesn't get too squeezed.</P>
  58  <P> To modify the legend you access the 'legend' property of the graph.
  59   For a full reference on all the possibilities (changing colors, layout,
  60   etc) see <A href="../ref/Legend.html#_C_LEGEND/">class legend</A> in
  61   the class reference</P>
  62  <P> For this we use the legends 'SetPos()' method as in<DIV class="phpscript">
  63  <CODE><FONT color="#000000"> <FONT color="#0000BB">&nbsp;$graph</FONT><FONT color="#007700">
  64  -&gt;</FONT><FONT color="#0000BB">legend</FONT><FONT color="#007700">-&gt;</FONT><FONT
  65  color="#0000BB">Pos</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">
  66  0.05</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">0.5</FONT><FONT
  67  color="#007700">,</FONT><FONT color="#DD0000">&quot;right&quot;</FONT><FONT color="#007700">
  68  ,</FONT><FONT color="#DD0000">&quot;center&quot;</FONT><FONT color="#007700">);</FONT><FONT
  69  color="#0000BB"></FONT></FONT></CODE></DIV></P>
  70  <P></P>
  71  <P> Doing this small modification will give the result shown below<DIV class="example">
  72  <BR> <A href="exframes/frame_example6.html" target="blank"><IMG border="0"
  73  HEIGHT="200"       src="img/img/img/img/img/img/example6.png" WIDTH="400"></A>
  74  <BR><B>Figure 13:</B> Adjusting the layout to give more rooms for the
  75   legend <A href="exframes/frame_example6.html" target="blank">[src]</A>&nbsp;
  76  <P></P>
  77  </DIV></P>
  78  <P> The above method 'SetPos()' deserves some explanation since it might
  79   not be obvious. You specify the position as a fraction of the overall
  80   width and height of the entire image. This makes it possible for you to
  81   resize the image within disturbing the relative position of the legend.
  82   We will later see that the same method is just to place arbitrary text
  83   in the image.</P>
  84  <P> To give added flexibility one must also specify to what edge of the
  85   legend the position given should be relative to. In the example above
  86   we have specified &quot;right&quot; edge on the legend for the for the horizontal
  87   positioning and &quot;center&quot; for the vertical position.</P>
  88  <P> This means that the right edge of the legend should be position 5 %
  89   of the image width from the right. If you had specified &quot;left&quot; the the
  90   legends left edge would be positioned 5 % of the image width from the
  91   image left side.</P>
  92  <P> By default the legends in the legend box gets stacked on top of each
  93   other. The other possibility is to have them sideways. To adjust this
  94   you use the <A href="../ref/Legend.html#_LEGEND_SETLAYOUT">SetLayout()</A>
  95   method. Using a horizontal layout with the previous example give the
  96   following result.<DIV class="example">
  97  <BR> <A href="exframes/frame_example6.1.html" target="blank"><IMG border="0"
  98  HEIGHT="240"       src="img/img/img/img/img/img/example6.1.png" WIDTH="300"></A>
  99  <BR><B>Figure 14:</B> Using a horizontal layout for the legends <A href="exframes/frame_example6.1.html"
 100  target="blank">[src]</A>&nbsp;
 101  <P></P>
 102  </DIV></P>
 103  <P></P>
 104  <H4>7.1.5.1 Adjusting the layout of the legend</H4>
 105  <P> For more advanced fomatting of the legend it is possible to adjust</P>
 106  <UL>
 107  <LI> The number of columns in the legend</LI>
 108  <LI> Specify vertical / horizontal margins for legend columns</LI>
 109  </UL>
 110  <P> In order to adjust the number of columns used in the legend the
 111   method<I> Legend::SetColumns</I> is used. So for example to have the
 112   legend lined up using three columns the follwing lines have to be added
 113   to teh script<DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
 114  &nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 115  legend</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
 116  SetColumns</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">3</FONT><FONT
 117  color="#007700">);</FONT><FONT color="#0000BB"></FONT></FONT></CODE></DIV>
 118  </P>
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