MATLAB help always showing true to if condition

3 次查看（过去 30 天）
Samyukta Ramnath
Samyukta Ramnath 2013-6-3
So, I wanted to write a program to classify text files based on their topic. The code below shows a very crude implementation of the same, but it isn't working properly. It is always showing a true value to the if condition, so I am getting Greetings four times and then Colloquial four times. What's up?
if true
File1 = fopen('Hello.xml','r');
File2 = fopen('Hello2.xml','r');
File3 = fopen('Colloquial1.xml','r');
File4 = fopen('Colloquial2.xml','r');
A = fscanf(File1, '%s');
B = fscanf(File2, '%s');
C = fscanf(File3, '%s');
D = fscanf(File4, '%s');
if ~( strcmp(A,'Hi') || strcmp(A,'Hello') || strcmp(A,'how'))
disp('Greetings.');
end
if ~( strcmp(B,'Hi') || strcmp(B,'Hello') || strcmp(B,'how'))
disp('Greetings');
end
if ~( strcmp(C,'Hi') || strcmp(C,'Hello') || strcmp(C,'how'))
disp('Greetings');
end
if ~( strcmp(D,'Hi') || strcmp(D,'Hello') || strcmp(D,'how'))
disp('Greetings');
end
if ~( strcmp(A,'lite'))
disp('Colloquial.');
end
if ~( strcmp(B, 'lite'))
disp('Colloquial');
end
if ~( strcmp(C, 'lite'))
disp('Colloquial');
end
if ~( strcmp(D, 'lite'))
disp('Colloquial');
end
end
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Samyukta Ramnath
Samyukta Ramnath 2013-6-4
But REGEXP is mainly for performing operations on the found substring, right? I just need to see if the word is there.
Daniel Shub
Daniel Shub 2013-6-4
No, REGEXPREP Does replacements, REGEXP just does the search.

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采纳的回答

Daniel Shub
Daniel Shub 2013-6-4
The strcmp function requires an exact match. We can define a simple test function to see if a string is either exactly 'Hi' or exactly 'lite'
test = @(A)([strcmp(A,'Hi'), strcmp(A,'lite')])
Then
test('Hi')
1 0
test('lite')
0 1
test('Hilite')
0 0
In words: Hi is Hi, but it is not lite. lite is not Hi but is lite, and Hilite is neither Hi nor lite.
Are you potentially looking for STRFIND
test = @(A)([~isempty(strfind(A,'Hi')), ~isempty(strfind(A,'lite'))])
test('Hi')
1 0
test('lite')
0 1
test('Hilite')
1 1
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Daniel Shub
Daniel Shub 2013-6-6
Please consider accepting an answer if your problem is solved. Also, please consider voting for other answers that were helpful.

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更多回答（2 个）

Ken Atwell
Ken Atwell 2013-6-3
It is not clear what the contents of the files are and what the expected ("correct") output ought to be. Be aware that strcmp returns different results than a C programmer might expect:
<http://www.mathworks.com/help/matlab/ref/strcmp.html>
strcmp might be returning 1 where you are expecting 0.
If that is not the problem, you will need to provide more context -- namely, the first line of the four files you are parsing.
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Ken Atwell
Ken Atwell 2013-6-3
Take out the not operators (the difference between MATLAB and C) and it seems to work okay for me:
File1 = fopen('Hello.xml','r');
File2 = fopen('Hello2.xml','r');
File3 = fopen('Colloquial1.xml','r');
File4 = fopen('Colloquial2.xml','r');
A = fscanf(File1, '%s');
B = fscanf(File2, '%s');
C = fscanf(File3, '%s');
D = fscanf(File4, '%s');
if strcmp(A,'Hi') || strcmp(A,'Hello') || strcmp(A,'how')
disp('Greetings A');
end
if strcmp(B,'Hi') || strcmp(B,'Hello') || strcmp(B,'how')
disp('Greetings B');
end
if strcmp(C,'Hi') || strcmp(C,'Hello') || strcmp(C,'how')
disp('Greetings C');
end
if strcmp(D,'Hi') || strcmp(D,'Hello') || strcmp(D,'how')
disp('Greetings D');
end
if strcmp(A,'lite')
disp('Colloquial A');
end
if strcmp(B, 'lite')
disp('Colloquial B');
end
if strcmp(C, 'lite')
disp('Colloquial C');
end
if strcmp(D, 'lite')
disp('Colloquial D');
end
if true
% code
end
Output is:
Greetings A
Greetings B
Colloquial C
Colloquial D
Samyukta Ramnath
Samyukta Ramnath 2013-6-4
Oh My. I copied and pasted this exact code into my MATLAB script and ran it, and nothing happened.

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Iain
Iain 2013-6-4
Do A, B, C, and D actually have those strings in them, EXACTLY like what you're comparing them to?
I suspect they have a different case. Try strcmpi instead of strcmp.
What do you get when you get matlab to print out A, B, C & D?

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