[Sommaire] [Imprimer]

   1  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
   2  <HTML>
   3  <HEAD>
   4  <META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=iso-iso-8859-1">
   5  <LINK REL="Start" HREF="index.html">
   6  <LINK REL="Contents" HREF="toc.html">
   7  <LINK REL="Prev" HREF="818Usinglogarithmicscale.html">
   8  <LINK REL="Next" HREF="8110Adjustingthegridlinesintheplot.html">
   9  <STYLE TYPE="text/css"><!--
  10  BODY { font-family: serif }
  11  H1 { font-family: sans-serif }
  12  H2 { font-family: sans-serif }
  13  H3 { font-family: sans-serif }
  14  H4 { font-family: sans-serif }
  15  H5 { font-family: sans-serif }
  16  H6 { font-family: sans-serif }
  17  SUB { font-size: smaller }
  18  SUP { font-size: smaller }
  19  PRE { font-family: monospace }
  20  A { text-decoration: none }
  21  --></STYLE>
  22  </HEAD>
  23  <BODY>
  24  <A HREF="toc.html">Contents</A>
  25  <A HREF="818Usinglogarithmicscale.html">Previous</A>
  26  <A HREF="8110Adjustingthegridlinesintheplot.html">Next</A>
  27  <HR NOSHADE>
  28  <H3><A NAME="8_1_9">8.1.9 More on scales</A></H3>
  29  <P> As you saw in the previous example it is possible to use different
  30   types of scales. In JpGraph you can use the following scales</P>
  31  <UL>
  32  <LI>Linear scale, the standard &quot;scale&quot;</LI>
  33  <LI>Logarithmic scale</LI>
  34  <LI>Integer scale, very similar to linear scale but restricts the scale
  35   values (and labels) to integer values.</LI>
  36  <LI>Text scale, Similar to integer scale and used when only the
  37   numbering of items is relevant. A text scale is almost exclusively used
  38   for the X-axis. A typical example for this is the X-axis for a bar
  39   plot. The labels for the text scale is usually replaced by user
  40   supplied texts. Text scales can only be used for the X-axis (it doesn't
  41   make sense for the Y-scale).</LI>
  42  </UL>
  43  <P> Any combination of these may be used. Linear and logarithmic scales
  44   are pretty straightforward. The text scale might deserve some
  45   explanation. The easiest way to think of the text scale is as a linear
  46   scale consisting of only natural numbers, i.e. 0,1,2,3,4,... . This
  47   scale is used when you just have a number of Y-values you want to plot
  48   in a consecutive order and don't care about the X-values. For the above
  49   example it will also work fine to use a linear X-scale (try it!).
  50   However, the scale is now treated as consisting or real numbers so the
  51   auto scaling, depending on the size of the image an the number of data
  52   points, might decide to display other labels then the natural numbers.,
  53   i.e. a label might be 2.5 say. This is not going to happen if you use a
  54   text scale.</P>
  55  <P> The normal practice for text scale is to specify text strings as
  56   labels instead as the default natural numbers. You can specify text
  57   strings for the labels by calling the <A href="../ref/Axis.html#_AXIS_SETTICKLABELS">
  58   SetTickLabels()</A> method on the Axis.</P>
  59  <P> To specify the scale you use the <A href="../ref/Graph.html#_GRAPH_SETSCALE">
  60   SetScale()</A> method. A few examples might help clarify this.</P>
  61  <UL>
  62  <LI> &quot;textlin&quot;, text-scale for X-axis, Linear scale for Y-axis</LI>
  63  <LI> &quot;linlin&quot;, linear-scale for X-axis, Linear scale for Y-axis</LI>
  64  <LI> &quot;linlog&quot;, linear-scale for X-axis, Logarithmic scale for Y-axis</LI>
  65  <LI> &quot;loglog&quot;, Logarithmic scale for X-axis, Logarithmic scale for
  66   Y-axis</LI>
  67  <LI> &quot;textint&quot;, text-scale for X-axis, Integer scale for Y-axis</LI>
  68  <LI> &quot;textlog&quot;, Text scale for X-axis, Logarithmic scale for Y-axis</LI>
  69  </UL>
  70  <P> As you can see all your graphs will require at least one call to
  71   SetScale() in the beginning of your script. Normally it will come right
  72   after the creation of the Graph().</P>
  73  <P> To specify the scale for the Y2 axis you use the <A href="../ref/Graph.html#_GRAPH_SETY2SCALE">
  74   SetY2Scale()</A> Since you only specify one axis you only specify
  75   &quot;half&quot; of the string in the previous examples. So to set a logarithmic
  76   Y2 scale you will call
  77  <!--?
  78  $t ='$grap-->
  79   SetY2Scale(&quot;log&quot;);'; ShowCodeSnippet($t); ?&gt;</P>
  80  <HR NOSHADE>
  81  <A HREF="toc.html">Contents</A>
  82  <A HREF="818Usinglogarithmicscale.html">Previous</A>
  83  <A HREF="8110Adjustingthegridlinesintheplot.html">Next</A>
  84  </BODY>
  85  </HTML>