Call of textscan or strfind function takes long time for first time while running in loop [matlab 2020b on linux centos]

3 次查看(过去 30 天)
We are trying to read a file which has repeatedly 9 rows of text followed by 200000 particle trajectories. A piece of code, enough to produce the problem is:
fname = abc.txt;
fid = fopen(fname,'r');
for ii = 1:20
InputText=textscan(fid,'%s',9,'delimiter','\n');
ii
pp = InputText{1};
Nrows = pp{4}
aa =textscan(fid,'%d %d %f %f %f %f', ... % Read data block
'delimiter',',');
end
apparently, to print ii = 1, it takes 10 seconds while rest all calls in loop finish in 1-2 seconds. It clearly indicates that trouble is on first call of textscan and not with subsequent calls.
The same issue is with strfind function if i put in loop.
I checked on matlab and the answers suggest either license issue or graphics issue. I ran matlab with no-desktop and still got the same issue. I checked it with Nvidia and opengl software choice and issue persists.
Kindly help resolving.
  1 个评论
dpb
dpb 2021-7-14
InputText=textscan(fid,'%s',9,'delimiter','\n');
ii
pp = InputText{1};
Nrows = pp{4}
looks peculiar -- you read as char() data but then use the content as numeric without a conversion operation.

请先登录,再进行评论。

采纳的回答

Walter Roberson
Walter Roberson 2021-7-14
Specify the file encoding when you do the fopen(), or else it will scan the entire file checking to see if any utf8 is present

更多回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Data Import and Export 的更多信息

产品


版本

R2020b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by