Assigned Octave variable not being saved to file - octave

Question

In the Octave script below I am looping through files in a directory, loading them in to Octave to do some manipulation on data, and then attempting to write the manipulated data ( a matrix ) to a new file whose name is derived from the name of the input file. The manipulated data is assigned to a variable name that has the same name as the file that it is to be saved in. All unwanted variables are cleared and the save command should save/write the single, assigned variable matrix to the file "new_filename."
However, this last save/write command is not happening, and I don't understand why not. Without specific variable commands, the save function should save all variables in scope, in this case there only being the one matrix to save. Why is this not working?
clear all ;
all_raw_OHLC_files = glob( "*_raw_OHLC_daily" ) ; % cell with filenames matching *_raw_OHLC_daily
for ii = 1 : length( all_raw_OHLC_files ) % loop for length of above cell
filename = all_raw_OHLC_files{ii} ; % get files' names
% create a new filename for the output file
split_filename = strsplit( filename , "_" ) ;
new_filename = tolower( [ split_filename{1} "_" split_filename{2} "_ohlc_daily" ] ) ;
% open and read file
fid = fopen( filename , 'rt' ) ;
data = textscan( fid , '%s %f %f %f %f %f %s' , 'Delimiter' , ',' , 'CollectOutput', 1 ) ;
fclose( fid ) ;
ex_data = [ datenum( data{1} , 'yyyy-mm-dd HH:MM:SS' ) data{2} ] ; % extract the file's data
% process the raw data in to OHLC bars
weekday_ix = weekday( ex_data( : , 1 ) ) ;
% find Mondays immediately preceeded by Sundays in the data
monday_ix = find( ( weekday_ix == 2 ) .* ( shift( weekday_ix , 1 ) == 1 ) ) ;
sunday_ix = monday_ix .- 1 ;
% replace Monday open with the Sunday open
ex_data( monday_ix , 2 ) = ex_data( sunday_ix , 2 ) ;
% replace Monday high with max of Sunday high and Monday high
ex_data( monday_ix , 3 ) = max( ex_data( sunday_ix , 3 ) , ex_data( monday_ix , 3 ) ) ;
% repeat for min of lows
ex_data( monday_ix , 4 ) = min( ex_data( sunday_ix , 4 ) , ex_data( monday_ix , 4 ) ) ;
% combines volume figures
ex_data( monday_ix , 6 ) = ex_data( sunday_ix , 6 ) .+ ex_data( monday_ix , 6 ) ;
% now delete the sunday data
ex_data( sunday_ix , : ) = [] ;
assignin( "base" , tolower( [ split_filename{1} "_" split_filename{2} "_ohlc_daily" ] ) , ex_data )
clear ans weekday_ix sunday_ix monday_ix ii filename split_filename fid ex_data data all_raw_OHLC_files
% print to file
save new_filename
endfor

Answer 1

save new_filename saves the current workspace to a file with the filename "new_filename". I guess what you want is to create a file with a filename that is stored in "new_filename":
save (new_filename);
Your current approach of "clearing all I don't need and then store the whole workspace" is IMHO very ugly and you should instead explicitly store ex_data if this is the only part wou want:
save (new_filename, "ex_data");