%DICT Dictonary data storage. Stores data by key/value pairs.
% Creates a key/value dictionary similar to the DICT object in Python.
% Keys and values may be any valid Matlab data type.
%
% Examples:
% x=dict; % Create dictionary object
% x(12)='hello'; % Store value.
% x('hi')=[1 2 3]; % Store value.
%
% x('hi') % Lookup value
% ans =
% 1 2 3
%
% x(12) % Lookup value
% ans =
% hello
%
% lookup(x,12) % Lookup value
% ans =
% hello
%
% Other methods:
% KEYS - Returns cell array of all keys.
% VALUES - Returns cell array of all values.
%
% ISEMPTY - Returns true if dictionary is empty.
% LENGTH - Returns number of elements stored in dictionary.
% ISKEY - Determines if a key exists in dictionary.
% INDEX - Returns index of key in key array.
%
% PLUS - Combines two dictionaries.
% MINUS - Creates dictionary of unique keys.
% RMKEY - Removes key/value pair from dictionary.
%
% RENAME - Renames a key.
%
% Credits: Inspired by and based on LOOKUPTABLE by Dan Cohn, available on
% Matlab Central:
% http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=19381&objectType=file
%
% Written by: Doug Harriman (doug <dot> harriman <at> gmail <dot> com)
% 25-Apr-08 - Added RENAME.
% 20-Apr-08 - '.' access to methods working. Allethods have help text.
% Added '+' and '-' methods to composite DICT's.
% 03-Apr-08 - More methods to make more similar to Python dict object.
% 02-Apr-08 - Initial version.
classdef dict < handle
properties (SetAccess=protected)
% Cell arrays to hold keys and values of any Matlab data type
key = {};
value = {};
end % properties - protected
methods
function val = subsref(obj,ref)
%DICT/SUBSREF Subscript referencing for DICT objects.
%
% See also: DICT
%
% Re-implement dot referencing.
if strcmp(ref(1).type,'.')
% User trying to access a property or method.
% Property access
props = fieldnames(struct(obj));
if ismember(ref(1).subs,props)
val = obj.(ref.subs);
return;
end
% Methods access
if ismember(ref(1).subs,methods(obj))
if length(ref) > 1
% Call with args
val = obj.(ref(1).subs)(ref(2).subs{:});
else
% No args
val = obj.(ref.subs);
end
return;
end
% User trying to access something else.
error(['Reference to non-existant property or method ''' ref.subs '''']);
end
if ~strcmp(ref.type,'()')
error('Cell indexing not supported.');
end
% Vectorized calls not supported
if length(ref.subs) > 1
error('DICT only supports storing key/value pairs one at a time.');
end
key = ref.subs{1};
val = lookup(obj,key);
end % subsref
function obj = subsasgn(obj,ref,value)
%DICT/SUBSASGN Subscript assignment for DICT objects.
%
% See also: DICT
%
if ~strcmp(ref.type,'()')
error('Cell and dot indexing for assignment not supported.');
end
% Vectorized calls not supported
if length(ref.subs) > 1
error('DICT only supports storing key/value pairs one at a time.');
end
key = ref.subs{1};
% Existing or new key?
idx = index(obj,key);
if isempty(idx)
% New
idx = length(obj.key) + 1;
end
obj.key{idx} = key;
obj.value{idx} = value;
end % subsasgn
function val = length(obj)
%DICT/LENGTH Number of key/value pairs in dictionary.
%
% See also: DICT
%
val = length(obj.key);
end
function idx = index(obj,key)
%DICT/INDEX Find index of a key in the dictionary key array.
%
% See also: DICT
%
idx = cellfun(@(x)isequal(x,key),obj.key);
idx = find(idx);
end % index
function [] = disp(obj)
%DICT/DISP Display a DICT object.
%
% See also: DICT
%
disp(' Dictionary:');
disp(struct(obj));
end % disp
% DISPLAY
function [] = display(obj)
%DICT/DISPLAY Display a DICT object.
%
% See also: DICT
%
disp(obj);
end
function val = lookup(obj,key)
%DICT/LOOKUP Return a value given a key.
%
% See also: DICT, DICT/INDEX
%
% Make sure key exists
idx = index(obj,key);
if isempty(idx)
val = [];
return;
end
% Extract value
val = obj.value(idx);
val = val{1};
end
function data = keys(obj)
%DICT/KEYS Returns cell array of all keys in a DICT object.
%
% See also: DICT, DICT/VALUES
%
data = obj.key';
end % keys
function data = values(obj)
%DICT\VALUES Returns cell array of all values in a DICT object.
%
% See also: DICT, DICT/KEYS
%
data = obj.value';
end % values
function tf = iskey(obj,keys)
%DICT/ISKEY Returns bool array denoting if key(s) exist in dictionary.
%
% See also: DICT, DICT/KEYS
%
if ~iscell(keys)
keys = {keys};
end
nkeys = length(keys);
tf = false(nkeys,1);
for i = 1:nkeys
key = keys{i};
tf(i) = any(cellfun(@(x)isequal(x,key),obj.key));
end
end % iskey
function obj = rmkey(obj,key)
%DICT/RMKEY Removes a key/value pair from a dictionary by key.
%
% See also: DICT, DICT/ISKEY
%
idx = index(obj,key);
obj.key(idx) = [];
obj.value(idx) = [];
% Make the display look nice
if isempty(obj.key)
obj.key = {};
obj.value = {};
end
end % rmkey
function tf = isempty(obj)
%DICT/ISEMPTY Returns true if dictionary isempty.
%
% See also: DICT, DICT/KEYS
%
tf = isempty(obj.key);
end % isempty
function obj1 = plus(obj1,obj2)
%DICT/PLUS Creates composite dictionary.
% DICT1+DICT2 returns a dictionary composed of key value pairs
% from both DICT1 and DICT2. If both dictionaries contain the
% same key, the value stored in DIC1 will be used.
%
% See also: DICT, DICT/MINUS, DICT/KEYS, DICT/ISKEY
%
% Error check inputs
error(nargchk(2,2,nargin));
if ~isa(obj2,'dict')
error('Both inputs must be DICT objects.');
end
% Look for key collisions
idx = obj1.iskey(obj2.keys);
% Tack on unique keys and values to x.
obj1.key = {obj1.key{:} obj2.key{~idx}};
obj1.value = {obj1.value{:} obj2.value{~idx}};
end % plus
function obj1 = minus(obj1,obj2)
%DICT/MINUS Creates dictionary of unique keys.
% DICT1-DICT2 returns a dictionary composed of key value pairs
% which have keys that only exist in DICT1.
%
% See also: DICT, DICT/PLUS, DICT/KEYS, DICT/ISKEY
%
% Error check inputs
error(nargchk(2,2,nargin));
if ~isa(obj2,'dict')
error('Both inputs must be DICT objects.');
end
% Look for key collisions
idx = ~obj2.iskey(obj1.keys);
% Tack on unique keys and values to x.
obj1.key = obj1.key(idx);
obj1.value = obj1.value(idx);
end % minus
function obj = rename(obj,key_old,key_new)
%DICT/RENAME Renames a key.
% RENAME(DICT,KEY_OLD,KEY_NEW)
%
% See also: DICT, DICT/ISKEY
%
idx = index(obj,key_old);
if isempty(idx)
return;
end
obj.key{idx} = key_new;
end % rename
end % methods
end % classdef
