@Section
   @Title { Introduction }
   @Tag { pie_intr }
@Begin
@PP
The Lout definitions for pie graph formatting are kept in a file called
{@Code "pie"}, which you must include at the start of your document if
pie.file @Index { @Code "pie" setup file }
you want pie graphs, like this:
@ID -1px @Break @OneRow @Code {
"@SysInclude { pie }"
"@SysInclude { doc }"
"@Doc @Text @Begin"
"..."
"@End @Text"
}
Setup files for specialized packages, such as {@Code "pie"}, should be
included before the main setup file.  Once this is done, the @Code "@Pie"
symbol used below will then be available for use anywhere within your
document.  As usual in Lout, the @Code "@Pie" symbol produces an object
which may appear anywhere at all -- in a centred display, for example,
or in a figure, or as an entry in a table.
@PP
A pie graph is made by a @Code "@Pie" symbol enclosing a sequence of
@Code "@Slice" symbols.  These @Code "@Slice" symbols and their options
are the only things that may appear inside the @Code "@Pie" symbol.
@PP
Every option of @Code "@Slice" is also an option of {@Code "@Pie"}.
Giving a value to such an option at @Code "@Pie" will make that
the default value for very {@Code "@Slice"}.  For example,
you can write
@ID -1px @Break @OneRow @Code @Verbatim {
@Pie
    weight { 20 }
{
    ...
}
}
to give every slice a weight (angular extent) of 20.  If all but a
few slices have the same weight, you can still do this, just giving
a @Code weight option to the exceptional slices.
@PP
Furthermore, every option of @Code "@Pie" appears in the setup
file, and giving a value to an option there makes that value the
default value for every @Code "@Pie" in your document.  For example,
if you want every slice of every pie to be light red, you can set
the @Code paint option in the setup file to {@Code lightred},
and all your slices will be painted this colour unless you
override the setup file value by giving @Code paint options to
some pies or slices.
@PP
See Section @NumberOf setup to find out how to make your own copy
of the setup file, perhaps calling it {@Code mypie}, and change
some options within it.  Your document would then typically
start like this:
@ID -1px @Break @OneRow @Code {
"@Include { mypie }"
"@SysInclude { doc }"
"@Doc @Text @Begin"
"..."
"@End @Text"
}
and by changing options within file @Code "mypie" you can
affect every pie graph in your document.
@End @Section
