Two small changes

MATLAnswer.m

@@ -930,7 +930,7 @@ function plots(varargin)
             % now that they are all answers
             answers = cat(1, answers{:});
 
-            isMATL = ~cellfun(@isempty, regexp({answers.body}, '^MATL'));
+            isMATL = ~cellfun(@isempty, regexp({answers.body}, '^\s*MATL'));
             answers = answers(isMATL);
 
             % Now we want the actual content from the answers
@@ -943,7 +943,7 @@ function plots(varargin)
 
             for k = 1:ceil(numel(answers) / chunksize)
                 chunk = answers(((k - 1) * chunksize + 1) : ...
-                                (min(k * chunksize - 1, numel(answers))));
+                                (min(k * chunksize, numel(answers))));
 
                 ids = sprintf('%d;', chunk.answer_id);
                 url = strcat(MATLAnswer.API_URL, '/answers/', ids(1:end-1));

extend_file.m

@@ -0,0 +1,47 @@
+function x = extend_file(existing_file, date_start)
+
+% function x = extend_file(existing_file, date_start )
+%
+% Extends a file containing an MATLAnswer object named `x,` to include newer answers. The file name
+% is specified as the char vector `existing_file`. The second input, `date_start`, indicates a
+% date, in format '2018-06-20', up to which that file contains answers. The file is assumed to contain
+% all answers corresponding to dates before the specified date. On the other hand, newer answers may
+% exist in the specified date, or after the date, that are not in the file; and those will get included.
+%
+% This is useful because often it is not possible to download all answers up to the current date
+% (probably because they are too many and the Stack Exchange API imposes some limitation in the number
+% of answers that can be downloaded).
+%
+% This script downloads new answers starting from the specified date (which must be the date in which
+% the existing file was generated), and merges the new and the old. When merging, older duplicates
+% are removed. Duplicates arise if the existing file contains some answers in the specified date or
+% after that. Those answers will be downloaded again, and the old version should be removed.
+%
+% Note that answers in the site before the specified may have changed and will not be updated. Only
+% answers newer than the specified date are downloaded. If the existing file contains answers up to
+% date D2, and an earlier date D1 is specified as `date_start`, answers from D1 to D2 will get updated.
+%
+% So the idea is to specify `date_start` as old as possible, to update existing answers in
+% addition to include the new answers.
+%
+% Example use: x = extend_file('12viii18.mat', '2018-01-15');
+%
+% Luis Mendo
+
+load(existing_file, 'x');
+assert(logical(exist('x', 'var')), 'File does not contain a variable named x')
+x_old = x;
+x_new = MATLAnswer.fetch('fromdate', date_start); % 1 is most recent, end is earliest
+x = [x_new; x_old]; % from most recent to earliest
+x = flip(x); % from earliest to recent
+creationDate = cellfun(@datenum, {x.CreationDate}); % convert from datetime to number. Thanks to the
+% previous flip, this will be an increasing vector
+[~, ind_keep] = unique(creationDate, 'last'); % 'last', together with the fac that creationDate is
+% increasing, ensures we keep the most recently obtained version of each duplicate
+ind_remove = setdiff(1:numel(x), ind_keep);
+disp(['Removing ' num2str(numel(ind_remove)) ' duplicate answers; dates from ' ...
+    datestr(x(ind_remove(1)).CreationDate, 1)  ' to ' datestr(x(ind_remove(end)).CreationDate, 1)])
+disp(['The result contains ' num2str(numel(ind_keep)) ' answers'])
+x = x(ind_keep);
+x = flip(x); % undo previous flip, so that most recent appears first, as returned by MATLAnswer
+% save(datestr(now,1), 'x')