Select/ Short rows from ASCII files

Hello,

I work with very large ASCII file, as the below sample

STOCK DATE TIME PRICE

ETE 04/01/2010 10170000 18.54 430 Big Cap

ABC 04/01/2010 10190000 18.34 200 Big Cap

YYY 04/01/2010 10200000 18.34 100 Big Cap

which is TAB delimited and sorted by TIME as above.

How can I select rows with respect to the column 'STOCK'

for instance selecting only the rows for the stock 'ABC' ?

In case these are not then sorted by time, how can I sort them by TIME?

Many thanks in advance.

Panos

Answer 1

[Fangjun Jiang]

Import your ASCII file first. If you could make the data like the format below, it's straightforward to use ismember() and sort() function to achieve what you want.

Data={'ETE' '04/10/2010 10170000' 18.54 430 'Big Cap';
'ABC' '04/01/2010 10190000' 18.34 200 'Big Cap';
'YYY' '04/01/2010 10200000' 18.34 100 'Big Cap';
'ABC' '04/02/2010 10190000' 18.54 300 'Big Cap';}

Ind=ismember(Data(:,1),'ABC')
Stock_ABC=Data(Ind,:)

[Trash,Ind]=sort(datenum(Data(:,2),'mm/dd/yyyy HHMMSSFFF'));
Stock_Sorted=Data(Ind,:)

[Pap]

The thing is that it is a very large ASCII file. (almost 9,000,000 rows) so I cant make the data as the format above

Thanks

Panos

[Fangjun Jiang]

I don't mean to manually type into that format. You can use uiimport(),importdata(), xlsread() or textscan() to import your ASCII file and then make your data into a cell array.

Answer 2

[Pap]

Thanks so much Fangjun!

Is there any way to export the result in a new ASCII file?

Panos

[Fangjun Jiang]

Yes. xlswrite() can write a cell array to an Excel file which I think would be better for this type of information. You can also use csvwrite(), dlmwrite() to write to an ASCII text file.