How to import some large data please

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Mate 2u
Mate 2u 2013-12-24
评论： Mate 2u 2014-1-5
Hi all I have a file called DJ.csv which has 5 columns. 1) Dates (01/02/2007), 2) Times (30.42.0), 3) prices 12553, 12442, 4) Codes (DJ123) and 5) trade size.
I want to take column 3 and 5 (price and trade size into matlab). I am having some trouble as the csv is quite big.
I tried this:
fileID = fopen('K:\test\test\DJ.csv');
A = fread(fileID,'double');
fclose(fileID);
But it only gives me a vector of values which are not the same as my data. Any help would be very much appreciated.
Thanks.
  1 个评论
Mate 2u
Mate 2u 2013-12-24
As a note, importdata works, but it is not suitable for very large files.

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dpb
dpb 2013-12-25
编辑：dpb 2013-12-26
fread is for stream unformatted files; you have formatted delimited file--
doc textscan % and friends
If you really only want/need the two columns sotoo (air-code, untested)
[p,s]=textread('K:\test\test\DJ.csv','%*s%*s,%f%*f%f','delimiter',',');
ought to do unless the third column is indeed a comma-for-a-decimal point as well as a comma-delimited file. In that case you've got a problem. You'll have to read three values instead of just two or preprocess the file or otherwise handle the decimal separator as Matlab can't (and you can't expect it to) know the difference between comma-delimiters and decimal places.
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Walter Roberson
Walter Roberson 2014-1-3
datacell = textscan(fid,'%*s%*s%f%*s%f','delimiter',',');
The previous version had a stray comma in the format.

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