#############################################################################
##
#W io.xml
#Y Copyright (C) 2017 James D. Mitchell
##
## Licensing information can be found in the README file of this package.
##
#############################################################################
##
<#GAPDoc Label="IteratorFromGeneratorsFile">
<ManSection>
<Func Name = "IteratorFromGeneratorsFile" Arg = "filename"/>
<Returns>An iterator.</Returns>
<Description>
If <A>filename</A> is a file or a string containing the name of a file
created using <Ref Func = "WriteGenerators"/>, then
<C>IteratorFromGeneratorsFile</C> returns an iterator <C>iter</C> such that
<C>NextIterator(iter)</C> returns the next collection of generators stored
in the file <A>filename</A>. <P/>
This function is a convenient way of, for example, looping over a
collection of generators in a file without loading every object in the
file into memory. This might be useful if the file contains more
information than there is available memory.<P/>
If you want to get an iterator for a file written using
<C>WriteGenerators</C> from a version of &SEMIGROUPS; before version
3.0.0, then you can use <C>IteratorFromOldGeneratorsFile</C>.
</Description>
</ManSection>
<#/GAPDoc>
<#GAPDoc Label="WriteGenerators">
<ManSection>
<Func Name = "WriteGenerators" Arg = "filename, list[, append][, function]"/>
<Returns><C>IO_OK</C> or <C>IO_ERROR</C>.</Returns>
<Description>
This function provides a method for writing collections of elements of a
semigroup to a file. The resulting file can be further compressed using
<C>gzip</C> or <C>xz</C>.<P/>
The argument <A>list</A> should be a list of lists of elements, or
semigroups. <P/>
The argument <A>filename</A> should be a string containing the name of a
file or an <Package>IO</Package> package file object where the entries
in <A>list</A> will be written; see <Ref Func="IO_File"
BookName="io"/> and <Ref Func="IO_CompressedFile" BookName="io"/>.<P/>
If the optional third argument <A>append</A> is not present or is given
and equals <C>"w"</C>, then the previous content of the file is deleted
and overwritten. If the third argument is <C>"a"</C>, then <C>list</C>
is appended to the file. <P/>
If any element of <A>list</A> is a semigroup, then the generators of that
semigroup are written to <A>filename</A>. More specifically, the list
returned by <Ref Attr="GeneratorsOfSemigroup" BookName="ref"/> is written
to the file.
<P/>
This function returns
<Ref Var="IO_OK" BookName="io"/> if everything went well or
<Ref Var="IO_ERROR" BookName="io"/> if something went wrong.<P/>
The file produced by <C>WriteGenerators</C> can be read using <Ref Func = "ReadGenerators"/>.
<P/>
From Version 3.0.0 onwards the &SEMIGROUPS; package used the &IO; package
pickling functionality; see <Ref Sect="Pickling and unpickling"
BookName="io"/> for more details. This approach is used because it is
more general and more robust than the methods used by earlier versions of
&SEMIGROUPS;, although the performance is somewhat worse, and the
resulting files are somewhat larger. <P/>
</Description>
</ManSection>
<#/GAPDoc>
<#GAPDoc Label="ReadGenerators">
<ManSection>
<Func Name = "ReadGenerators" Arg = "filename[, nr]"/>
<Returns>A list of lists of semigroup elements.</Returns>
<Description>
If <A>filename</A> is an <Package>IO</Package> package file object or is
the name of a file created using
<Ref Func = "WriteGenerators"/>, then <C>ReadGenerators</C> returns the
contents of this file as a list of lists of elements of a semigroup. <P/>
If the optional second argument <A>nr</A> is present, then
<C>ReadGenerators</C> returns the elements stored in the <A>nr</A>th line
of <A>filename</A>.
<#GAPDoc Label="IteratorFromMultiplicationTableFile">
<ManSection>
<Func Name = "IteratorFromMultiplicationTableFile" Arg = "filename"/>
<Returns>An iterator.</Returns>
<Description>
If <A>filename</A> is a file or a string containing the name of a file
created using <Ref Func = "WriteMultiplicationTable"/>, then
<C>IteratorFromMultiplicationTableFile</C> returns an iterator <C>iter</C>
such that <C>NextIterator(iter)</C> returns the next multiplication table
stored in the file <A>filename</A>.<P/>
This function is a convenient way of, for example, looping over a
collection of multiplication tables in a file without loading every
object in the file into memory. This might be useful if the file
contains more information than there is available memory.<P/>
</Description>
</ManSection>
<#/GAPDoc>
<#GAPDoc Label="WriteMultiplicationTable">
<ManSection>
<Func Name = "WriteMultiplicationTable" Arg = "filename, list[, append]"/>
<Returns><C>IO_OK</C> or <C>IO_ERROR</C>.</Returns>
<Description>
This function provides a method for writing collections of multiplication
tables to a file. The resulting file can be further compressed using
<C>gzip</C> or <C>xz</C>. This function applies to square arrays with a
maximum of 255 rows where the entries are integers from
<C>[1, 2, .., n]</C> (where <C>n</C> is the number of rows in the
array.<P/>
The argument <A>list</A> should be a list of multiplication tables.<P/>
The argument <A>filename</A> should be a file or a string containing the
name of a file where the entries in <A>list</A> will be written or an
<Package>IO</Package> package file object; see <Ref Func="IO_File"
BookName="io"/> and <Ref Func="IO_CompressedFile" BookName="io"/>.<P/>
If the optional third argument <A>append</A> is not present or is
given and equals <C>"w"</C>, then the previous content of the file
is deleted and overwritten. If the third argument is given and equals
<C>"a"</C> then <C>list</C> is appended to the file. This function
returns <Ref Var="IO_OK" BookName="io"/> if everything went well or
<Ref Var="IO_ERROR" BookName="io"/> if something went wrong.<P/>
The multiplication tables saved in <A>filename</A> can be recovered from
the file using <Ref Func = "ReadMultiplicationTable"/>.
</Description>
</ManSection>
<#/GAPDoc>
<#GAPDoc Label="ReadMultiplicationTable">
<ManSection>
<Func Name = "ReadMultiplicationTable" Arg = "filename[, nr]"/>
<Returns>A list of multiplication tables.</Returns>
<Description>
If <A>filename</A> is a file or is the name of a file created using
<Ref Func = "WriteMultiplicationTable"/>, then
<C>ReadMultiplicationTable</C> returns the contents of this file as a
list of multiplication tables.<P/>
If the optional second argument <A>nr</A> is present, then
<C>ReadMultiplicationTable</C> returns the multiplication table stored in
the <A>nr</A>th line of <A>filename</A>. <!-- The next example is a log not an example because for some reason it
fails in the cygwin CI job -->
<Log><![CDATA[
gap> file := Concatenation(SEMIGROUPS.PackageDir,
> "/data/tst/tables.gz");;
gap> tab := ReadMultiplicationTable(file, 12);
[ [ 1, 1, 3, 4, 5, 6, 7, 8, 9, 6 ], [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ],
[ 3, 3, 1, 5, 4, 7, 6, 9, 8, 7 ], [ 4, 4, 9, 6, 3, 8, 5, 1, 7, 8 ],
[ 5, 5, 8, 7, 1, 9, 4, 3, 6, 9 ], [ 6, 6, 7, 8, 9, 1, 3, 4, 5, 1 ],
[ 7, 7, 6, 9, 8, 3, 1, 5, 4, 3 ], [ 8, 8, 5, 1, 7, 4, 9, 6, 3, 4 ],
[ 9, 9, 4, 3, 6, 5, 8, 7, 1, 5 ], [ 6, 10, 7, 8, 9, 1, 3, 4, 5, 2 ]
]]]></Log>
</Description>
</ManSection>
<#/GAPDoc>
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