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fread file with 4 bytes of prepended array size

3 vues (au cours des 30 derniers jours)
A
A le 7 Fév 2012
How do I read in a binary file(fread function) with data that has 4 bytes of data that specify the array size for each group of data. For example if I load the file using fread it would be 100x20 matrix but the first 4 bytes specify the area size(16 bytes). The file should read as 100x16. I'm currently using a for loop to read the file as start at byte 5, read 16, then start at byte 20, read 16, etc. Seems like their should be one line of code that says skip first 4 bytes of each data set. Thank you.
  1 commentaire
A
A le 7 Fév 2012
This works, but is it possible to optimize this code:
fseek(fid,4,'bof');
A =(fread(fid,[4,4],'*uint8',0,'n')).';
p=4;
for i= 1:100
p=p+20;
fseek(fid,p,'bof');
temp = (fread(fid,[4,4],'*uint8',0,'n')).';
A = cat(3,temp, A);
end

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Réponses (1)

Sean de Wolski
Sean de Wolski le 7 Fév 2012
Yes, fseek will be your friend.
  2 commentaires
A
A le 7 Fév 2012
yea, i'm using fseek within a for loop
Sean de Wolski
Sean de Wolski le 7 Fév 2012
preallocating A to its final size would be good. Why not just read all of the file in at once and reshape() after?

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