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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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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>4.7. Tuning Parameters</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-autorange.html" title="4.6. Plot Range and Tick Increment Calculations" /><link rel="next" href="adv-multiplot.html" title="4.8. Multiple Plots Per Image" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">4.7. Tuning Parameters</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="adv-autorange.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-multiplot.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-tuning"></a>4.7. Tuning Parameters</h2></div></div></div><div class="abstract"><p class="title"><strong></strong></p><p>
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This section documents some PHPlot class member variables that can be used
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to adjust the appearance of plots.
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You should rarely find it necessary to change these, and PHPlot does not
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provide "Set" functions for them.
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</p></div><p>
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The class member variables listed in <a class="xref" href="dev-vars.html#dev-vars-list" title="10.1. List of Member Variables">Section 10.1, “List of Member Variables”</a> are
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generally reserved for use only by the class implementation itself. But
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there are some adjustments you can make to the appearance of a plot only
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by changing member variables.
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This section documents some PHPlot class member variables that alter a plot
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appearance, but which do not have any defined class functions for you to
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use to set the values.
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</p><p>
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For example, if you want PHPlot to draw the X/Y grid above (after) the plot,
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rather than behind it, you would do the following:
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</p><pre class="programlisting">$plot = new PHPlot(800, 600);
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...
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$plot->grid_at_foreground = TRUE; // Draw grid after plot
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</pre><p>
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</p><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-bars"></a>4.7.1. Tuning Bar Charts</h3></div></div></div><p>
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These variables affect plot types <a class="link" href="conc-plottypes.html#plottype-bars" title="3.4.2. Plot Type: bars (Bar Plot)">bars</a>
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and <a class="link" href="conc-plottypes.html#plottype-stackedbars" title="3.4.15. Plot Type: stackedbars (Stacked Bar Plot)">stackedbars</a>.
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They are used to control the width of the bars.
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(For horizontal plots, the "width" of the bars is actually the height.)
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">bar_extra_space</code></span></dt><dd><p>
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Controls the amount of extra space within each group of bars. Default is 0.5,
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meaning 1/2 of the width of one bar is left as a gap, within the space
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allocated to the group (see <code class="varname">group_frac_width</code>).
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Increasing this makes each group of bars shrink together.
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Decreasing this makes the group of bars expand within the allocated space.
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</p></dd><dt><span class="term"><code class="varname">group_frac_width</code></span></dt><dd><p>
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Controls the amount of available space used by each bar group. Default is 0.7,
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meaning the group of bars fills 70% of the available space (but that includes
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the empty space due to <code class="varname">bar_extra_space</code>).
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Increasing this makes the group of bars wider.
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</p></dd><dt><span class="term"><code class="varname">bar_width_adjust</code></span></dt><dd><p>
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Controls the width of each bar. Default is 1.0.
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Decreasing this makes individual bars narrower, leaving gaps between the
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bars in a group. This must be greater than 0. If it is greater than 1, the
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bars will overlap.
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</p></dd></dl></div><p>
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If bar_extra_space=0, group_frac_width=1, and bar_width_adjust=1
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then all the bars touch (within each group, and adjacent groups).
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-boxes"></a>4.7.2. Tuning Box Plots</h3></div></div></div><p>
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These variables affect plot type <a class="link" href="conc-plottypes.html#plottype-boxes" title="3.4.3. Plot Type: boxes (Box Plot)">boxes</a>.
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(Box Plots were added in PHPlot-6.1.0.)
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">boxes_max_width</code></span></dt><dd><p>
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This is one half the maximum width of the boxes. The default is 8 pixels.
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</p></dd><dt><span class="term"><code class="varname">boxes_min_width</code></span></dt><dd><p>
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This is one half the minimum width of the boxes. The default is 2 pixels.
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</p></dd><dt><span class="term"><code class="varname">boxes_frac_width</code></span></dt><dd><p>
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This is the fractional amount of the available space (plot width area
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divided by number of points) to use for half the width of the boxes.
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The default is 0.3. This needs to be less than 0.5 or there will be
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overlap between adjacent boxes.
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</p></dd><dt><span class="term"><code class="varname">boxes_t_width</code></span></dt><dd><p>
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This is the ratio of the width of the 'T' ends of the whiskers to the
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width of the boxes. The default is 0.6, meaning the 'T' ends are 60%
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of the width of the boxes.
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</p></dd></dl></div><p>
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</p><p>
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PHPlot calculates the width of the boxes in a box plot in the same way as
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it does for OHLC and candlestick plots (see <a class="xref" href="adv-tuning.html#adv-tuning-ohlc" title="4.7.4. Tuning OHLC Charts">Section 4.7.4, “Tuning OHLC Charts”</a>).
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Half of the width of each box is:
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</p><pre class="programlisting">half_width = max(boxes_min_width, min(boxes_max_width, boxes_frac_width * avail_area))
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Where avail_area = plot_area_width / number_data_points
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</pre><p>
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-bubbles"></a>4.7.3. Tuning Bubble Plots</h3></div></div></div><p>
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These two variables set the range of bubble size in
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<a class="link" href="conc-plottypes.html#plottype-bubbles" title="3.4.4. Plot Type: bubbles (Bubble Plot)">bubbles</a> plots.
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">bubbles_min_size</code></span></dt><dd><p>
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Minimum bubble diameter in pixels.
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</p></dd><dt><span class="term"><code class="varname">bubbles_max_size</code></span></dt><dd><p>
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Maximum bubble diameter in pixels.
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</p></dd></dl></div><p>
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</p><p>
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The point with the smallest Z value will be drawn as a bubble with a diameter
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of bubbles_min_size, and the point with the largest Z value will be drawn as
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a bubble with a diameter of bubbles_max_size. That is, PHPlot linearly maps
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the range of Z values in the plot to the range of bubble sizes.
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</p><p>
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By default, the minimum bubble size is 6 pixels, and the maximum bubble
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size is 1/12 times the smaller of the plot area width and plot area height.
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For example, if the plot area is 800x600, the default maximum bubble size
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will be 50 pixels (600 / 12).
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-ohlc"></a>4.7.4. Tuning OHLC Charts</h3></div></div></div><p>
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These variables affect plot types <a class="link" href="conc-plottypes.html#plottype-ohlc" title="3.4.9. Plot Type: ohlc (Basic OHLC Plot)">ohlc</a>,
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<a class="link" href="conc-plottypes.html#plottype-candlesticks" title="3.4.5. Plot Type: candlesticks (OHLC Candlesticks Plot)">candlesticks</a>,
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and <a class="link" href="conc-plottypes.html#plottype-candlesticks2" title="3.4.6. Plot Type: candlesticks2 (OHLC Filled Candlesticks Plot)">candlesticks2</a>,
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For candlesticks plots, they adjust the calculation of the width of the
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candlestick body.
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For basic OHLC plots, they adjust the calculation of the length of the tick
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marks which represent opening and closing prices.
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(All of these were added in PHPlot-5.3.0.)
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">ohlc_max_width</code></span></dt><dd><p>
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This is one half the maximum width of the candlestick body, or
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the maximum length of an OHLC tick mark. The default is 8 pixels.
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</p></dd><dt><span class="term"><code class="varname">ohlc_min_width</code></span></dt><dd><p>
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This is one half the minimum width of the candlestick body, or
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the minimum length of an OHLC tick mark. The default is 2 pixels.
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</p></dd><dt><span class="term"><code class="varname">ohlc_frac_width</code></span></dt><dd><p>
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This is the fractional amount of the available space (plot width area
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divided by number of points) to use for half the width of the candlestick
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bodies or OHLC tick marks. The default is 0.3. This needs to be less than
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0.5 or there will be overlap between adjacent candlesticks.
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</p></dd></dl></div><p>
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</p><p>
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PHPlot calculates a value to use for one half the width of the candlestick
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bodies, or for the OHLC open/close tick mark lengths, as follows:
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</p><pre class="programlisting">half_width = max(ohlc_min_width, min(ohlc_max_width, ohlc_frac_width * avail_area))
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Where avail_area = plot_area_width / number_data_points
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</pre><p>
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-pie"></a>4.7.5. Tuning Pie Charts</h3></div></div></div><p>
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These variables adjusts the appearance of
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<a class="link" href="conc-plottypes.html#plottype-pie" title="3.4.10. Plot Type: pie (Pie Plot)">pie charts</a>.
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">pie_diam_factor</code></span></dt><dd><p>
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Diameter factor for shaded pie charts. This is the ratio of the height to
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the width of the pie. The default value is 0.5, meaning the pie chart will be
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drawn as an ellipse with height equal to half of its width.
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This variable is ignored for unshaded plots (see <a class="xref" href="SetShading.html" title="SetShading"><span class="refentrytitle">SetShading</span></a>),
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which are always circular (diameter factor of 1.0).
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</p></dd><dt><span class="term"><code class="varname">pie_min_size_factor</code></span></dt><dd><p>
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The minimum size of the pie in a pie chart, relative to the plot area size.
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When pie chart autosizing is on (see <a class="xref" href="SetPieAutoSize.html" title="SetPieAutoSize"><span class="refentrytitle">SetPieAutoSize</span></a>),
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and pie labels are located outside the pie chart (as they are by default),
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PHPlot will shrink the pie so the labels will fit inside the plot area.
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To prevent an overly long label from making the pie too small,
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PHPlot uses <code class="varname">pie_min_size_factor</code> to limit
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how small the pie will become.
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The default value is 0.5, meaning the pie chart will be no smaller than
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half the width or height of the plot area, even if that makes the labels
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fall partly off the image.
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</p><p>
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Setting this smaller allows the pie to be a smaller portion of the plot
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area, if long labels require the space. Setting this larger prevents the
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pie from becoming smaller in that case.
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Setting this to 1.0 is approximately equivalent to using
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<code class="literal">SetPieAutoSize(False)</code>. (The difference is that the
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later still leaves a small gap between the pie and the plot area boundary.)
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</p></dd></dl></div><p>
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-legend"></a>4.7.6. Tuning the Legend</h3></div></div></div><p>
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This variable adjusts the appearance of the legend.
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">legend_colorbox_width</code></span></dt><dd><p>
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This is an adjustment factor for the width of the color boxes in the legend.
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With the default value 1.0, the color boxes are as wide as one character in
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the font used in the legend (width of "E" for TrueType fonts).
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A value of 2.0 makes the color boxes twice as wide, and 0.5 makes them half
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the character width.
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(This was added in PHPlot-5.3.0.)
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</p><p>
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If point shapes are used in the legend instead of color boxes
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(see <a class="xref" href="SetLegendUseShapes.html" title="SetLegendUseShapes"><span class="refentrytitle">SetLegendUseShapes</span></a> - for points plots and similar),
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then <code class="literal">legend_colorbox_width</code> still adjusts the horizontal
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space allocated for the point shape. The point shape itself is not scaled,
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but is always drawn at the same size as in the plot itself. If the plot
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area has a color background, the width adjustment will stretch the
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box in that color which is drawn behind the point shape.
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</p><p>
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If line markers are used in the legend of instead of color boxes (see
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<a class="xref" href="SetLegendUseShapes.html" title="SetLegendUseShapes"><span class="refentrytitle">SetLegendUseShapes</span></a> - with line plots and similar),
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then <code class="literal">legend_colorbox_width</code> scales the horizontal
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space allocated for the line marker, but there is an additional factor
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of 4 applied by PHPlot.
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This leaves enough room to draw a line segment that can be identified
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visually by color and width.
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</p></dd></dl></div><p>
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-labels"></a>4.7.7. Tuning Labels</h3></div></div></div><p>
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These variables affect the appearance of labels.
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">data_value_label_angle</code></span></dt><dd><p>
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This sets the angle, in degrees, for the position of data value labels near
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the data points they label.
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Together with <code class="varname">data_value_label_distance</code>,
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it determines the position of the reference point for the label.
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(This does not apply to data value labels for bars or stackedbars plots, as
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the label position is fixed for these plot types.)
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The default is 90 degrees, which places the label above the data point.
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PHPlot automatically selects which text alignment to use, based on the angle.
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For example, with the default 90 degree angle, the label will
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be horizontally centered, vertically bottom aligned. If the angle is 0
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degrees, the alignment is horizontally left, vertically centered.
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</p></dd><dt><span class="term"><code class="varname">data_value_label_distance</code></span></dt><dd><p>
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This sets the distance, in pixels, for the position of data value labels near
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the data points they label.
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Together with <code class="varname">data_value_label_angle</code>,
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it determines the position of the reference point for the label.
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(This does not apply to data value labels for bars or stackedbars plots, as
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the label position is fixed for these plot types.)
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The default is 5 pixels.
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</p></dd></dl></div><p>
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</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a id="adv-tuning-misc"></a>4.7.8. Miscellaneous Tuning</h3></div></div></div><p>
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These variables affect other aspects of the appearance of a plot.
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</p><p>
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</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">grid_at_foreground</code></span></dt><dd><p>
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Controls the order in which certain plot elements are drawn. The default is
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FALSE, meaning the X axis, Y axis, and grid lines are drawn before the main
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part of the plot. If TRUE, the X axis, Y axis, and grid lines are drawn
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after the main part of the plot, which results in the grid lines overlaying
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the plotted data.
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</p></dd><dt><span class="term"><code class="varname">locale_override</code></span></dt><dd><p>
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Set this to TRUE (or any non-empty value) to prevent PHPlot from loading
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information about the locale from the operating system.
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You must do this if you want to override the locale using
|
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<code class="function">setlocale()</code> from your PHP code, perhaps because your
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platform does not allow setting the locale from environment variables.
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See <a class="xref" href="SetNumberFormat.html" title="SetNumberFormat"><span class="refentrytitle">SetNumberFormat</span></a> for more information.
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</p></dd><dt><span class="term"><code class="varname">safe_margin</code></span></dt><dd><p>
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This is the amount of space that PHPlot leaves between elements that
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should not touch. The default is 5 pixels. Changing this is not recommended.
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The effect is similar to changing the cellpadding on an HTML table.
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</p></dd></dl></div><p>
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