for loop with eval and sprintf with underscore in
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Sorry about that,
I've been trying really hard to find any solution from other answers, but or I don't understand them or it doesn't work.
I've also red that is bad to dynamically use 'eval' and 'sprintf', however, even though I'm willing to learn, I am not able to do in another way (and I've tried it).
I've many .txt file:
X12345678_1_ABC_ABCD_ABCDE_ABCDEF.txt
% Load .txt files into workspace
files = dir('*.txt');
for i=1:length(files);
eval(['load ' files(i).name ' -ascii']);
end
%% I dynamically try to do something with my variable
for i=1:length(files);
filename = files(i).name(1:end-4); %%%I get out the .txt
temp = eval(sprintf('X%s\_1\_ABC\_ABCD\_ABCDE\_ABCDEF',filename));
%insert the matrix of the text file into a new 3D matrix
threeD_matrix (i,:,f) = temp;
end
Warning: Escape sequence '_' is not valid. See 'help sprintf' for valid escape sequences. Error using eval Undefined function or variable
Thank you so much for your help!!!!!
1 个评论
"I've many .txt file: X12345678_1_ABC_ABCD_ABCDE_ABCDEF.txt"
The simple solution is to avoid LOAD for textfiles. Use READMATRIX, READTABLE, etc.
At the time this question was posted, CSVREAD or DLMREAD would likely have worked.
回答（2 个）
Jan
2014-4-7
Two general advices:
1. Avoid eval in general:
eval(['load ' files(i).name ' -ascii']);
Better:
load(files(i).name, '-ascii');
2. Join folder names by fullfile instead of sprintf with hard coded separators.
Star Strider
2014-4-7
编辑：Star Strider
2014-4-7
To put a backslash (\) into a string, you need to use a double backslash (\\):
filename = 'myfile.txt';
R = sprintf('X%s\\_1\\_ABC\\_ABCD\\_ABCDE\\_ABCDEF', filename)
produces:
R =
Xmyfile.txt\_1\_ABC\_ABCD\_ABCDE\_ABCDEF
The ‘eval’ function is not considered efficient programming practice, but it may be the only way to get a variable generated as a string into the workspace as a variable. It is not really ‘wrong’ though.
10 个评论
Elisa
2014-4-7
Star Strider
2014-4-7
To do that, just put them in as ordinary characters:
filename = 'myfile.txt';
R = sprintf('X%s_1_ABC_ABCD_ABCDE_ABCDEF', filename)
produces:
R =
Xmyfile.txt_1_ABC_ABCD_ABCDE_ABCDEF
Elisa
2014-4-7
Star Strider
2014-4-7
编辑：Star Strider
2014-4-7
I believe I’m beginning to understand what you’re doing. To find out what the variables are in your ‘.mat’ files, see the documentation for that version of whos and its friends. (NOTE that there is also a version of whos that operates in a different context but provides the same sort of information. This is the first time I realised there are actually two versions of that function, so thanks!)
I’m not certain what you want to do after you load your files. If this isn’t the direction you want to go with them or the variables in them (since I have no idea how they’re organised and what they contain), please describe in some detail what you want to do.
Star Strider
2014-4-7
My pleasure!
I’m nevertheless still a bit lost.
What happens if you just write:
disp(X12345678_1_ABC_ABCD_ABCDE_ABCDEF)
Does it display the contents of the variable? If so, the variable is already in your workspace.
Since I get the impression that this may actually be a file name, see what this does:
which X12345678_1_ABC_ABCD_ABCDE_ABCDEF -all
If it’s a file in MATLAB’s path, that should find it. You may have to change that to:
which X12345678_1_ABC_ABCD_ABCDE_ABCDEF.txt -all
or whatever its extension is. The function version of that command will return the entire file path:
datfile = which('X12345678_1_ABC_ABCD_ABCDE_ABCDEF.txt')
or
datfile = which('X12345678_1_ABC_ABCD_ABCDE_ABCDEF.txt','-all')
Star Strider
2014-4-7
移动：Voss
2023-11-14
My pleasure!
Sorry for the delay — sleeping here (GMT-6).
Star Strider
2014-4-7
My pleasure!
Sorry for the delay — sleeping here (GMT-6).
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