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<A HREF="toc.html">Contents</A>
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<HR NOSHADE>
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<H3><A NAME="8_1_4">8.1.4 Adding a second Y-scale</A></H3>
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<P> As you saw in the preceding example you could add multiple plots to
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the same graph and Y-axis. However what if the two plots you want to
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display in the graph has very different ranges. One might for example
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have Y-values like above but the other might have Y-values in the
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100:s. Even though it is perfectly possible to add them as above the
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graph with the smallest values will have a very low dynamic range since
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the scale must accomplish the bigger dynamic range of the second plot.</P>
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<P> The solution to this is to use a second Y-axis with a different
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scale and add the second plot to this Y-axis instead. Let's take a look
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at how that is accomplished.</P>
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<P> First we need to create a new data array with large values and
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secondly we need to specify a scale for the Y2 axis. This is done by
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the lines<DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
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$y2data </FONT><FONT color="#007700">= array(</FONT><FONT color="#0000BB">
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354</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">200</FONT><FONT
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color="#007700">,</FONT><FONT color="#0000BB">265</FONT><FONT color="#007700">
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,</FONT><FONT color="#0000BB">99</FONT><FONT color="#007700">,</FONT><FONT
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color="#0000BB">111</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">
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91</FONT><FONT color="#007700">,</FONT><FONT color="#0000BB">198</FONT><FONT
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color="#007700">,</FONT><FONT color="#0000BB">225</FONT><FONT color="#007700">
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,</FONT><FONT color="#0000BB">293</FONT><FONT color="#007700">,</FONT><FONT
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color="#0000BB">251</FONT><FONT color="#007700">);
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<BR></FONT><FONT color="#0000BB">$graph</FONT><FONT color="#007700">-></FONT><FONT
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color="#0000BB">SetY2Scale</FONT><FONT color="#007700">(</FONT><FONT color="#DD0000">
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"lin"</FONT><FONT color="#007700">);</FONT><FONT color="#0000BB"></FONT></FONT>
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</CODE></DIV></P>
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<P> and finally we create a new line plot and add that to the second
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Y-axis. Note that we here use a new method, AddY2(), since we want this
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plot to be added to the second Y-axis. Note that JpGraph will only
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support two different Y-axis. This is not considered a limitation since
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using more than two scales in the same graph would make it very
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difficult to interpret the meaning of the graph.</P>
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<P> To make the graph a little bit more esthetic pleasing we use
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different colors for the different plots and let the two different
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Y-axis get the same colors as the plots.</P>
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<P> The resulting graph is shown below. source)<DIV class="example">
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<BR> <A href="exframes/frame_example5.html" target="blank"><IMG border="0"
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HEIGHT="200" src="img/example5.png" WIDTH="300"></A>
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<BR><B>Figure 10:</B> Adding a second Y-scale plot to the same graph <A href="exframes/frame_example5.html"
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target="blank">[src]</A>
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<P></P>
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</DIV></P>
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<P></P>
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<HR NOSHADE>
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<A HREF="toc.html">Contents</A>
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<A HREF="813Addingseveralplotstothesamegraph.html">Previous</A>
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<A HREF="815Addingalegendtothegraph.html">Next</A>
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