Error undefined variable or method

2012 10 5
2 个回答
6 次查看（30 天）

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I am working on LDA-Latent Dirichlet Allocation for Images,in that the first step is to find
K-dimensional topic weight vector m from the distribution p(|) = Dirichlet().
i tried Dirichlet(I),where I is the Image
but i get error
Undefined function or method 'Dirichlet' for input arguments of type 'char'.
please help

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回答（2 个）

Wayne King
Wayne King 2012-10-5

0 个投票

It is not a MathWorks' function. The extract that you supplied seems to suggest that you are sampling from a Dirichlet distribution. If you search the web, there are MATLAB routines available for sampling from a Dirichlet distribution.
Walter Roberson
Walter Roberson 2012-10-5

0 个投票

You are misreading the document as if it is telling you a MATLAB function name, when instead it is naming a particular mathematical distribution without regards to how that is implemented.
MATLAB does not provide a Dirichelet random distribution function, but see http://www.mathworks.com/matlabcentral/newsreader/view_thread/65818

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kash
kash 2012-10-5
But walter can we form a Topic from this LDA,,,,,for example if we have a image example forest and if assign k =2 ,is it possible to form two topics from those 2 classes..if the image consisite of forest ,can we form topics as 80%water 20%of land ,my image is
http://imgur.com/zhqJX
Walter Roberson
Walter Roberson 2012-10-5
I have no idea; I have no experience in that topic. I have experience in googling phrases to find the original line and seeing that a key word was left out in a posting.
kash
kash 2012-10-5
ok walter considering that image is it possible to say that the image consists of water and land
Walter Roberson
Walter Roberson 2012-10-5
No. It could be, for example, an image of the surface of Saturn's moon Enceladus
kash
kash 2012-10-5
ok walter can you please tell how LDA can be assigned to form topics from Images or from bag of words
Image Analyst
Image Analyst 2012-10-5
This is an algorithm question more than a MATLAB programming question. I suggest you find remote sensing forums where people do this kind of image analysis. Or search the VisionBib for papers related to your scene. Neither Walter nor I do remote sensing.
Walter Roberson
Walter Roberson 2012-10-5
Q: In the movie Star Wars, how large is the Imperial Battle Cruiser?
A: About 3 feet long. It just looks huge because of the camera angles and very very careful use of perspective.
You need to distinguish between what an image looks like and what the image is. An image might perfectly match the remote sensing characteristics for water and land, but the image might be something else completely, such as CGI.

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kash
kash
2012-10-5

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