Application of codes on big ASCII file.

Question

Pap 2011-4-4

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/4748-application-of-codes-on-big-ascii-file

Hi all,

% I work the below code serie :

% Read stock data from file fid = fopen('stocks.txt'); data = textscan(fid,'%s%s%f%f%f% [^\n]','delimiter',' ','headerlines',1);

% Read as text (for later writing)

frewind(fid);
txt = textscan(fid,'%s','delimiter','\n');
fclose(fid);

% Get prices from imported data

Price = data{4};

% Determine which stocks to buy

buy = [true;diff(Price)>=0];
idx = find(~diff(Price));
buy(idx+1) = buy(idx);

% Make string of trade decision

buysell = cellstr(repmat(' Sell',size(Price)));
buysell(buy) = {' Buy'};

% Open file for writing

fid = fopen('stocks2.txt','wt');

% Make output string by appending trade decision

outstr = strcat(txt{1},[' Trade';buysell]);

% Write out

fprintf(fid,'%s\n',outstr{:});
fclose(fid);

However, while the above works perfectly with a small ASCII file (example), it seems not to work with a big ASCII (almost 540 MB).

Actually when I try to define the column 'Price' (column 4) for imported data, I get a value ' [ ]' while I expeceted something like '15000000x1 double' ,since the ASCII consists of nearly 15000000 rows. ( When the above is applied to the sample ASCII, I indeed receive a 830281x1 double value, since the rows are 830281). As such I can't also the 'idx' code.

I can't also define 'data', 'txt', 'buysell' and 'outstr' since the created cell arrays are 6x1, 2x1 etc and not applicable to the total rows.

Is there any way to overcome this problem and work with such a file?

Many thanks in advantage,

Panos