Mercurial > hg > octave-lyh
changeset 12596:5161d02c96b7 stable
doc: Add help text for dynamic naming "(var)" of structure fields.
* container.txi: Add help text. Rename "Data Structures" to just "Structures"
* octave.texi: Rename "Data Structures" to just "Structures"
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Tue, 12 Apr 2011 13:48:07 -0700 |
| parents | 68eb9713b550 |
| children | e12a7c0a1fc5 |
| files | doc/interpreter/container.txi doc/interpreter/octave.texi |
| diffstat | 2 files changed, 49 insertions(+), 11 deletions(-) [+] |
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--- a/doc/interpreter/container.txi +++ b/doc/interpreter/container.txi @@ -28,13 +28,13 @@ another data container, the comma separated list. @menu -* Data Structures:: +* Structures:: * Cell Arrays:: * Comma Separated Lists:: @end menu -@node Data Structures -@section Data Structures +@node Structures +@section Structures @cindex structures @cindex data structures @@ -370,12 +370,50 @@ @node Creating Structures @subsection Creating Structures +@cindex dynamic naming -As well as indexing a structure with ".", Octave can create a structure -with the @code{struct} command. @code{struct} takes pairs of arguments, -where the first argument in the pair is the fieldname to include in the -structure and the second is a scalar or cell array, representing the -values to include in the structure or structure array. For example: +Besides the index operator ".", Octave can use dynamic naming "(var)" or the +@code{struct} function to create structures. Dynamic naming uses the string +value of a variable as the field name. For example, +@example +@group +a = "field2"; +x.a = 1; +x.(a) = 2; +x + @result{} x = + @{ + a = 1 + field2 = 2 + @} +@end group +@end example + +More realistically, all of the functions that operate on strings can be used +to build the correct field name before it is entered into the data structure. + +@example +@group +names = ["Bill"; "Mary"; "John"]; +ages = [37; 26; 31]; +for i = 1:rows (names) + database.(names(i,:)) = ages(i); +endfor +database + @result{} database = + @{ + Bill = 37 + Mary = 26 + John = 31 + @} +@end group +@end example + +The third way to create structures is the @code{struct} command. @code{struct} +takes pairs of arguments, where the first argument in the pair is the fieldname +to include in the structure and the second is a scalar or cell array, +representing the values to include in the structure or structure array. For +example: @example @group @@ -414,7 +452,7 @@ @end example If you want to create a struct which contains a cell array as an -individual field, you have to put it into another cell array like in +individual field, you must wrap it in another cell array as shown in the following example: @example