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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><title>4.8. Multiple Plots Per Image</title><link rel="stylesheet" type="text/css" href="phplotdoc.css" /><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /><link rel="home" href="index.html" title="PHPlot Reference Manual" /><link rel="up" href="advanced.html" title="Chapter 4. PHPlot Advanced Topics" /><link rel="prev" href="adv-tuning.html" title="4.7. Tuning Parameters" /><link rel="next" href="adv-streaming.html" title="4.9. Streaming Plots" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">4.8. Multiple Plots Per Image</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="adv-tuning.html">Prev</a> </td><th width="60%" align="center">Chapter 4. PHPlot Advanced Topics</th><td width="20%" align="right"> <a accesskey="n" href="adv-streaming.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adv-multiplot"></a>4.8. Multiple Plots Per Image</h2></div></div></div><div class="abstract"><p class="title"><strong></strong></p><p>
This section contains information about producing more than one plot on an
image.
  </p></div><p>
Using PHPlot, you can produce more than one plot on a single image.  These can
be <span class="emphasis"><em>tiled plots</em></span> - separate plots manually positioned within
the image, or <span class="emphasis"><em>overlay plots</em></span>.
Tiled plots are used when you want to display more than one plot on a single
image, for example side-by-side.
Overlay plots are used when you want to show more than one type or range
of data representation on a single plot.  For example, an overlay plot could
be used to show two data sets with different Y scales, or to overlay a bar
chart with a line plot.
You can also combine tiled and overlay plots in a single image.
</p><p>
An example of two tiled plots on an image can be found in
<a class="xref" href="ex-twoplot1.html" title="5.18. Example - Two Plots on One Image">Section 5.18, &#8220;Example - Two Plots on One Image&#8221;</a>.
An example of an overlay plot can be found in
<a class="xref" href="ex-outbreak.html" title="5.34. Example - Overlaying Plots">Section 5.34, &#8220;Example - Overlaying Plots&#8221;</a>
</p><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-multiplot-overview"></a>4.8.1. Overview of Multiple Plots</h3></div></div></div><p>
When producing multiple plots on an image, a single PHPlot object is used.
The overall steps to be followed are:
  </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>
Create a <code class="function">PHPlot</code> or <code class="function">PHPlot_truecolor</code>
object (referred to here as <code class="literal">$plot</code>).
      </p></li><li class="listitem"><p>
Use <code class="literal">$plot-&gt;SetPrintImage(False)</code> to disable automatic
output of the image after a plot is created.
      </p></li><li class="listitem"><p>
Prepare the first plot, including setting the data array, plot type, and any
other applicable settings.
      </p></li><li class="listitem"><p>
Use <code class="literal">$plot-&gt;DrawGraph()</code> when complete. 
This creates the plot, but does not produce any output.
      </p></li><li class="listitem"><p>
Repeat the previous two steps to prepare each additional plot, completing
it with <code class="literal">$plot-&gt;DrawGraph()</code>.
      </p></li><li class="listitem"><p>
When all the plots are complete, use <code class="literal">$plot-&gt;PrintImage()</code> to
output the completed image.
      </p></li></ol></div><p>
</p><p>
The sections which follow contain additional information you will need
to produce multiple plots on a single image.
</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-multiplot-settings"></a>4.8.2. Plot Settings with Multiple Plots</h3></div></div></div><p>
In general, PHPlot applies settings made for one plot as defaults for the
next plot, when using the same PHPlot class instance.
There are some special cases, however, which are discussed in the
sections below.
</p><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-global"></a>4.8.2.1. Global Settings</h4></div></div></div><p>
Certain plot elements apply to the image as a whole, not to individual plots.
PHPlot will draw these at most once per image. (That is, the element will be
drawn only the first time <code class="literal">DrawGraph()</code> is called after the
element has been set up.)
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
Main title (<a class="xref" href="SetTitle.html" title="SetTitle"><span class="refentrytitle">SetTitle</span></a>)
    </p></li><li class="listitem"><p>
Image background color (<a class="xref" href="SetBackgroundColor.html" title="SetBackgroundColor"><span class="refentrytitle">SetBackgroundColor</span></a>)
or image background file (<a class="xref" href="SetBgImage.html" title="SetBgImage"><span class="refentrytitle">SetBgImage</span></a>)
    </p></li><li class="listitem"><p>
Image border (<a class="xref" href="SetImageBorderColor.html" title="SetImageBorderColor"><span class="refentrytitle">SetImageBorderColor</span></a> and
<a class="xref" href="SetImageBorderType.html" title="SetImageBorderType"><span class="refentrytitle">SetImageBorderType</span></a>)
    </p></li></ul></div><p>
For example, the first plot on an image that has a main title will result in
the main title being drawn. If any subsequent plot (using the same PHPlot
instance) also sets a main title, that will be ignored.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-datascale"></a>4.8.2.2. Data Scaling</h4></div></div></div><p>
Whether you use <a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a> to set the plot area
data range, or you let PHPlot calculate the plot area data range,
that range applies to all subsequent plots unless overridden.
Even if you set a new data array, the calculated or pre-set data range from
the previous plot applies. Without being told otherwise, PHPlot will not
re-examine the data array to recalculate the data range.
This allows you to re-use an automatically calculated data range, if you want.
  </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
Nothing related to world coordinates and data scaling applies to pie charts,
which have do not use world coordinates.
    </p></div><p>
</p><p>
If instead you want PHPlot to automatically calculate the data range for
additional plots, call <code class="literal">SetPlotAreaWorld()</code> (with no
arguments), or <code class="literal">SetPlotAreaWorld(NULL, NULL, NULL, NULL)</code>.
Either of these forms causes PHPlot to forget about a specified or
calculated data range, and it will compute a new range.
</p><p>
Of course, you can also use <a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a> with
parameter values, to manually set all or part of the data range for each plot.
Any parameters you do not set (or specify as NULL) will be calculated based
on the data array for the current plot.
That is, PHPlot will forget about the previous data range once you call
<a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a>, regardless of how many non-NULL parameters
you use.
</p><p>
When overlaying plots, you will often want all the plots to use the same
data scale, so the values can be read off of the axis. Another option is to
have two separate Y scales, with one represented on the left side and one
on the right side. (See <a class="xref" href="ex-outbreak.html" title="5.34. Example - Overlaying Plots">Section 5.34, &#8220;Example - Overlaying Plots&#8221;</a> for an example of
overlaying plots with two different Y scales.)
In some cases it may make sense to overlay plots with different scales and
no separate axis, for example when using data value labels, or when the
important information is the trend or shape shown by the graph rather than
the actual values.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-plotarea"></a>4.8.2.3. Plot Area</h4></div></div></div><p>
You can specify a plot area (window) with <a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a>
or <a class="xref" href="SetMarginsPixels.html" title="SetMarginsPixels"><span class="refentrytitle">SetMarginsPixels</span></a>, or you can let PHPlot calculate a
plot area.
Whether you set the plot area yourself, or you let PHPlot calculate
it, those settings apply to all subsequent plots unless overridden.
</p><p>
This means that if you are doing side-by-side (tiled) plots on an image,
you must use <a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a> or
<a class="xref" href="SetMarginsPixels.html" title="SetMarginsPixels"><span class="refentrytitle">SetMarginsPixels</span></a> with each plot, to set
the area of the image to be used for that plot.
Remember that the plot area does not include the axis labels, tick marks,
or titles, so you must leave enough room between and around plots for these.
</p><p>
If you are doing overlay plots, you can let PHPlot calculate the plot area
for the first plot, or you can specify the area with
<a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a> or <a class="xref" href="SetMarginsPixels.html" title="SetMarginsPixels"><span class="refentrytitle">SetMarginsPixels</span></a>.
You need not use these for subsequent plots; PHPlot will continue to use the
same window, overlaying the additional plots.
</p><p>
However, if you allow PHPlot to calculate the plot area, it will only use
information in the first plot to determine the margins.
This will not work well if subsequent plots require more margin space.
For example, if the first plot has a Y axis title and tick labels only on the
left side, and the second overlay plot has a Y axis title and tick labels
on the right side, automatic plot area calculation will only leave enough
margin space on the left side.  As a result, the right side Y axis title and
tick labels may fall off the image edge.  To avoid this, use either
<a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a> or <a class="xref" href="SetMarginsPixels.html" title="SetMarginsPixels"><span class="refentrytitle">SetMarginsPixels</span></a>
to specify large enough margins.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-ticks"></a>4.8.2.4. Tick Increment</h4></div></div></div><p>
Tick increments are recalculated for each plot, based on the data range, unless
set with <a class="xref" href="SetXTickIncrement.html" title="SetXTickIncrement"><span class="refentrytitle">SetXTickIncrement</span></a>
or <a class="xref" href="SetYTickIncrement.html" title="SetYTickIncrement"><span class="refentrytitle">SetYTickIncrement</span></a>.
'Data range' here refers to that set with <a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a>,
or automatically calculated.
This differs from the way PHPlot handles the data range, which is not
recalculated by default after the first plot.
</p><p>
For overlay plots, if you want to use the same tick increments,
you should either set the desired tick increment (doing this for the first
plot is sufficient), or make sure the data ranges match.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-grid"></a>4.8.2.5. Grid Lines</h4></div></div></div><p>
PHPlot defaults to drawing the dependent variable grid (usually Y), and the
grid lines will be drawn at tick positions.
As stated above, the tick positions by default will be recalculated for
each plot, using the calculated or explicitly set data range.
</p><p>
For overlay plots, you generally do not want to have more than one set of
grid lines in each of X and Y, or the results will be confusing.  Even if
your plot overlays have the same tick increments, avoid having the grid
lines drawn more than once. Otherwise, the grid lines for the second plot
will overlay the plotted data from the first plot.
You can turn off the grid lines with <code class="literal">SetDrawXGrid(False)</code>
and <code class="literal">SetDrawYGrid(False)</code>.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-legend"></a>4.8.2.6. Legend Positioning</h4></div></div></div><p>
Legend position with multiple plots works differently depending on whether
the position is defaulted or set, and if set what method was used.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
If the legend position is defaulted, a legend will be drawn at the upper
right corner of each plot.
The same legend will be drawn in each position, unless the contents are
changed with <a class="xref" href="SetLegend.html" title="SetLegend"><span class="refentrytitle">SetLegend</span></a>.
    </p></li><li class="listitem"><p>
If the legend position is specified using device coordinates with
<a class="xref" href="SetLegendPixels.html" title="SetLegendPixels"><span class="refentrytitle">SetLegendPixels</span></a>, or by using
<a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a> (PHPlot-5.4.0 or later) with mode 'image'
or 'title', then the legend position is relative to the image.
The legend will be drawn at the specified position on the image,
once per plot, at the same location.
This repeated over-drawing is usually harmless,
but if you want to have it drawn only once,
either use <a class="xref" href="SetLegend.html" title="SetLegend"><span class="refentrytitle">SetLegend</span></a> only before the last plot,
or use either <code class="literal">SetLegend(NULL)</code>
or <code class="literal">SetLegend(array())</code>
to cancel the legend after the first plot.
    </p></li><li class="listitem"><p>
If the legend position is specified using world coordinates with
<a class="xref" href="SetLegendWorld.html" title="SetLegendWorld"><span class="refentrytitle">SetLegendWorld</span></a>, or by using
<a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a> (PHPlot-5.4.0 or later) with mode 'world'
or 'plot', then the legend position is relative to the plot or the data
within the plot.
The legend will be drawn at the calculated position on each plot.
If using <a class="xref" href="SetLegendWorld.html" title="SetLegendWorld"><span class="refentrytitle">SetLegendWorld</span></a>, or
<a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a> with mode 'world', this assumes the
specified world coordinates are within the plot area for each plot.
As with the default positioning case, the same legend will be drawn for
each plot, unless the contents are changed with
<code class="function">SetLegend()</code>.
    </p></li></ul></div><p>
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-background"></a>4.8.2.7. Plot Area Background</h4></div></div></div><p>
If you set a plot area background color with <a class="xref" href="SetPlotBgColor.html" title="SetPlotBgColor"><span class="refentrytitle">SetPlotBgColor</span></a>
and <a class="xref" href="SetDrawPlotAreaBackground.html" title="SetDrawPlotAreaBackground"><span class="refentrytitle">SetDrawPlotAreaBackground</span></a>,
or if you set a plot area background image with
<a class="xref" href="SetPlotAreaBgImage.html" title="SetPlotAreaBgImage"><span class="refentrytitle">SetPlotAreaBgImage</span></a>,
this will be applied to each plot until disabled.
This works well for side-by-side (tiled) plots, as each will get the same
background by default.
</p><p>
If you are overlaying multiple plots on an image, setting a plot area
background color or image for one plot will result in that background
hiding previous plots. Therefore, you need to set up the background for the
first plot, then turn it off it for the second plot.
If you previously set a plot area background image, you can disable it for
subsequent plots with <code class="literal">SetPlotAreaBgImage(NULL)</code>.
If you previously set and enabled a plot area background color, you can
disable it for subsequent plots with
<code class="literal">SetDrawPlotAreaBackground(FALSE)</code>.
</p></div><div class="sect3"><div class="titlepage"><div><div><h4 class="title"><a id="adv-multiplot-axis"></a>4.8.2.8. Axis Positioning</h4></div></div></div><p>
You can position the X and Y axis manually with
<a class="xref" href="SetXAxisPosition.html" title="SetXAxisPosition"><span class="refentrytitle">SetXAxisPosition</span></a> and <a class="xref" href="SetYAxisPosition.html" title="SetYAxisPosition"><span class="refentrytitle">SetYAxisPosition</span></a>,
or you can let PHPlot calculate the axis positions for you.
Whether you set the positions yourself, or let PHPlot calculate them for you,
those positions apply to subsequent plots unless overridden.
Even if you set a new data array, PHPlot will not recalculate the axis
positions unless told to.
</p><p>
If you want PHPlot to automatically re-calculate the X axis position for a
subsequent plot, use <code class="literal">SetXAxisPosition()</code> (with no
arguments), or <code class="literal">SetXAxisPosition('')</code>.
To restore automatic Y axis position calculation, use
<code class="literal">SetYAxisPosition()</code>
or <code class="literal">SetYAxisPosition('')</code>.
</p></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-multiplot-tiled"></a>4.8.3. Summary - Tiled Multiple Plots</h3></div></div></div><p>
Here are some guidelines for tiling multiple plots:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
Unless all plots will use the same X and Y data ranges, use
<a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a> with each plot.
Call the function with no arguments to have PHPlot automatically calculate
the data range for the plot, or supply arguments to explicitly set a data range.
    </p></li><li class="listitem"><p>
Use <a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a> to set the area within the image
for each plot. Remember to leave room for axis labels and titles.
    </p></li><li class="listitem"><p>
If you want a legend for each plot, use <a class="xref" href="SetLegendPixels.html" title="SetLegendPixels"><span class="refentrytitle">SetLegendPixels</span></a>,
<a class="xref" href="SetLegendWorld.html" title="SetLegendWorld"><span class="refentrytitle">SetLegendWorld</span></a>, or <a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a>
to position it.
Or let the position default to the upper right corner of each plot.
If instead you want a single legend, for example outside all the plot areas,
either set it up for the last plot, or
set it up for any plot and cancel it for the next plot.
Position the single legend with <a class="xref" href="SetLegendPixels.html" title="SetLegendPixels"><span class="refentrytitle">SetLegendPixels</span></a>,
or with <a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a> using any mode except 'world'.
    </p></li><li class="listitem"><p>
You can only have one main title for the entire image.
    </p></li></ul></div><p>
</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-multiplot-overlay"></a>4.8.4. Summary - Overlay Multiple Plots</h3></div></div></div><p>
Here are some guidelines for overlaying multiple plots:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
All plots will use the same data scaling by default, whether automatically
calculated by PHPlot or set with <a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a>.
Use <a class="xref" href="SetPlotAreaWorld.html" title="SetPlotAreaWorld"><span class="refentrytitle">SetPlotAreaWorld</span></a> if you want different data scaling
for subsequent plots.
    </p></li><li class="listitem"><p>
You can let PHPlot calculate the plot window by default, but it will not
account for additional margin space needed by plots after the first.
Instead, you can use <a class="xref" href="SetPlotAreaPixels.html" title="SetPlotAreaPixels"><span class="refentrytitle">SetPlotAreaPixels</span></a> or
<a class="xref" href="SetMarginsPixels.html" title="SetMarginsPixels"><span class="refentrytitle">SetMarginsPixels</span></a>
to set a specific plot area to use for all plots.
    </p></li><li class="listitem"><p>
Set the tick increments you want for each plot, especially if the data
ranges differ. You can have two sets of tick marks and labels if you position
them on the opposite sides of the plot area.
    </p></li><li class="listitem"><p>
Draw grid lines, if you want them, only for the first plot, and turn them
off for the second plot.
    </p></li><li class="listitem"><p>
If you want a single legend, either set it up for the last plot, or
set it up for any plot and cancel it for the next plot.
If you want multiple legends, one per overlay, position them
manually with <a class="xref" href="SetLegendWorld.html" title="SetLegendWorld"><span class="refentrytitle">SetLegendWorld</span></a>,
<a class="xref" href="SetLegendPixels.html" title="SetLegendPixels"><span class="refentrytitle">SetLegendPixels</span></a>, or <a class="xref" href="SetLegendPosition.html" title="SetLegendPosition"><span class="refentrytitle">SetLegendPosition</span></a>.
    </p></li><li class="listitem"><p>
If you want a plot area background, you must set it for the first plot
and cancel it for the second plot, or it will hide the plots.
    </p></li></ul></div><p>
</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-multiplot-history"></a>4.8.5. Multiple Plots - History</h3></div></div></div><p>
A number of fixes were made in PHPlot-5.3.1 that affect multiple plots
per image. If you are creating multiple plot images using PHPlot-5.3.0 or
earlier, you should upgrade to the latest release. If you are unable to
upgrade, you may need to work around the following issues:

</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
Color allocation: In PHPlot-5.2.0 and PHPlot-5.3.0, the data color array
(whether defaulted or set with <a class="xref" href="SetDataColors.html" title="SetDataColors"><span class="refentrytitle">SetDataColors</span></a>) was truncated
to the number of colors required for a plot.
This means that the additional colors were not available for subsequent plots,
so the data colors would repeat.
For example, if plot #1 used 3 colors for 3 data sets, and plot #2 had 5
data sets, only 3 colors were available and the first two colors would be
reused for the 4th and 5th data sets.
To work around this, you can reload the data colors before each subsequent plot.
To reload the default data colors, use
<code class="literal">$plot-&gt;SetDataColors(False)</code>.
Another work-around is to define a custom data color callback, which
turns off the color slot optimization.
    </p></li><li class="listitem"><p>
Legend positioning using <a class="xref" href="SetLegendWorld.html" title="SetLegendWorld"><span class="refentrytitle">SetLegendWorld</span></a> was not correctly
applied to subsequent plots in an image through PHPlot-5.3.0.
If you have multiple side-by-side plots and you want the legend in the same
world coordinate position in each plot, you still need to use
<code class="literal">SetLegendWorld(..., ...)</code> when creating each plot.
    </p></li><li class="listitem"><p>
Through PHPlot-5.3.0, there was no way to reset the X axis position or Y
axis position to the default of automatic positioning.
That is, <code class="literal">SetXAxisPosition()</code>,
<code class="literal">SetXAxisPosition('')</code>,
<code class="literal">SetYAxisPosition()</code>,
and <code class="literal">SetYAxisPosition('')</code> did not work.
There is no work-around to get automatic positioning of the axis lines.
    </p></li><li class="listitem"><p>
Through PHPlot-5.3.0, several functions had more restricted usage
when resetting to defaults.
      </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem"><p>
Use <code class="literal">SetLegendPixels(NULL, NULL)</code>
rather than <code class="literal">SetLegendPixels()</code>.
          </p></li><li class="listitem"><p>
Use <code class="literal">SetNumXTicks('')</code> and <code class="literal">SetNumYTicks('')</code>
rather than <code class="literal">SetNumXTicks()</code> and
<code class="literal">SetNumYTicks()</code>.
          </p></li><li class="listitem"><p>
Use <code class="literal">SetLegend(array())</code>
rather than <code class="literal">SetLegend(NULL)</code>.
          </p></li></ul></div><p>
    </p></li></ul></div><p>
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