I try to understand in general how sLDA works. In contrast to LDA, it has 'a response variable associated with each document'. Is each document labeled just by one topic in training set or it might be labeled by multiple topics?
If it must use just one topic as label for one document, is there another LDA model which takes as input several labels for each document in training set?
If sLDA might use more then one topic as label, is there any implementation (in Python, R, C/C++, Matlab) for sLDA with multi-labels?
sLDA has a response variable that is a label, but that really has nothing to do directly with the topics. The topics are still inferred exactly as they are with regular LDA, using probability calculations to build up N topics. Each document ends up with a vector of length N indicating how strongly it "contains" each topic. In sLDA it goes one step further - where it also in the model internally correlates the response label with the topics, to be able to predict what the response label should be for a never before seen document based upon its topic vector.
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Is it rational to use topic modelling for a single document or to be more precise is it mathematically okay to use LDA-gibbs method for a single document.If so what should be value of k and seed.
Also what is be the role of k and seed for single as well as large set of documents.
K and SEED are variable of the function LDA (in r studio).
Also let me know if I am wrong anywhere in this question.
To tell about my project ,I am trying to find out the main topics which can be used to represent the content of a single document.
I have already tried using k=4,7,10.Part of my question also is what value of k should be better.
It really depends on the document. A document could be a 700 page book or a single sentence. Your k is also going to be dependent on the document I think you mean the number of topics? If your document is the entire Wikipedia corpus 1500 topics might be appropriate if your document is a list of comments about movies then 20 topics might be appropriate. Optimizing that number can be done using the elbow method check out 17.
Seed can be pretty random it's just a leaver so your results can be replicated - it runs if you leave it blank. I would say try it and check your coherence, eyeball your topics and if it looks right then sure you can train an LDA on one document. A single document should process pretty fast.
Here is an example in python of using seed parameters. My data set is 1,048,575 rows note the seed is much higher:
ldamallet = gensim.models.wrappers.LdaMallet(mallet_path, corpus=bow_corpus,
num_topics=20, alpha =.1, id2word=dictionary, iterations = 1000,
random_seed = 569356958)
I am learning CUDA from the Udacity's course on parallel programming. In a quiz, they have a given a problem of sorting a pre-ranked variable(player's height). Since, it is a one-one correspondence between input and output array, should it not be a Map communication pattern instead of a Scatter?
CUDA makes no canonical definition of these terms, that I know of. Therefore my answer is merely a suggestion of how it might be or have been interpreted.
"Since, it is a one-one correspondence between input and output array"
This statement doesn't appear to be supported by the diagram, which shows gaps in the output array, which have no corresponding input point associated with them.
If a smaller set of values are distributed into a larger array (with resultant gaps in the output array, therefore, in which no input value corresponds to the gap location(s)), then a scatter might be used to describe that operation. Both scatters and maps have maps which describe where the input values go, but it might be that the instructor has defined scatter and map in such a way as to differentiate between these two cases, such as the following plausible definitions:
Scatter: one-to-one relationship from input to output (ie. unidirectional relationship). Every input location has a corresponding output location, but not every output location has a corresponding input location.
Map: one-to-one relationship between input and output (ie. bidirectional relationship). Every input location has a corresponding output location, and every output location has a corresponding input location.
Gather: one-to-one relationship from output to input (ie. unidirection relationship). Every output location has a corresponding input location, but not every input location has a corresponding output location.
The definition of each communication pattern (map, scatter, gather, etc.) varies slightly from one language/environment/context to another, but since I have followed that same Udacity course I'll try to explain that term as I understand it in the context of the course:
The Map operation calculates each output element as a function of its corresponding input element, i.e.:
output[tid] = foo(input[tid]);
The Gather pattern calculates each output element as a function of one or more (usually more) input elements, not necessarily the corresponding one (typically these are elements from a neighborhood). For example:
output[tid] = (input[tid-1] + input[tid+1]) / 2;
Lastly, the Scatter operation has each input element contribute to one or more (again, usually more) output elements. For instance,
atomicAdd( &(output[tid-1]), input[tid]);
atomicAdd( &(output[tid]), input[tid]);
atomicAdd( &(output[tid+1]), input[tid]);
The example given in the question is clearly not a Map, because each output is calculated from an input at a different location.
Also, it is hard to see how the same example can be a scatter, because each input element only causes one write to the output, but it is indeed a scatter because each input causes a write to an output whose location is determined by the input.
In other words, each CUDA thread processes an input element at the location associated with its tid(thread ID number), and calculates where to write the result. More usually a scatter would write on several places instead of only one, so this is a particular case that might as well be named differently.
Each player has 3 properties (name, height, rank).
So I think scatter is correct, because we should consider these three things to make output.
If player has only one property like rank,
then Map is correct I think.
reference: Parallel Communication Patterns Recap in this lecture
reference: map/reduce/gather/scatter with image
I have been trying to convert my level-1 S-function to level-2 but I got stuck at calling another subfunction at function Output(block) trying to look for other threads but to no avail, do you mind to provide related links?
My output depends on a lot processing with the inputs, this is the reason I need to call the sub-function in order to calculate and then return output values, all the examples that I can see are calculating their outputs directly in "function Output(block)", in my case I thought it is not possible.
I then tried to use Interpreted Matlab Function block but failed due to the output dimension is NOT the same as input dimension, also it does not support the return of more than ONE output................
Dear Sir/Madam,
I read in S-function documentation that "S-function level-1 supports vector inputs and outputs. DOES NOT support multiple input and output ports".
Does the second sentence mean the input and output dimension MUST BE SAME?
I have been using S-function level-1 to do the following:
[a1, b1] = choose_cells(c, d);
where a1 and b1 are outputs, c and d are inputs. All the variables are having a single value, except d is an array with 6 values.
Referring to the image attached, we all know that in S-function block, the input dimension must be SAME as output dimension, else we will get error, in this case, the input dimension is 7 while the output dimension is 2, so I have to include the "Terminator" blocks in the diagram for it to work perfectly, otherwise, I will get an error.
My problem is, when the system gets bigger, the array d could contain hundreds of variables, using this method, it means I would have to add hundreds of "Terminator" blocks in order to get this work, this definitely does not sound practical.
Could you please suggest me a wise way to implement this?
Thanks in advance.
http://imgur.com/ib6BTTp
http://imageshack.us/content_round.php?page=done&id=4tHclZ2klaGtl66S36zY2KfO5co
Are there any rules that you follow to determine the order of function arguments? For example, float pow(float x, float exponent) vs float pow(float exponent, float x). For concreteness, C++ could be used, but the question is valid for all programming languages.
My main concern is from the usability point of view, not runtime performance.
Edit:
Some possible bases for ordering could be:
Inputs versus Output
The way a "formula" is usually written, i.e., arguments from left-to-write.
Specificity to the argument to the context of the function, i.e., whether it is a "general" argument, e.g., a singleton object of the system, or specific.
In the example you cite, I think the order was decided on the basis of the mathematical notation xexponent, in which the base is written before the exponent and becomes the left parameter.
I'm not aware of any really sound general principle other than to try to imagine what your users will expect and/or easily remember. People aren't even wholly agreed whether you should write (source, destination) or (destination, source) when copying (compare std::copy with std::memcpy), although I'm pretty sure that the former is now much more common.
There are a whole lot of general conventions, though, followed to different extents by different people:
if the function is considered primarly to act upon a particular object, put it first
parameters that are considered to "configure" the operation of the function come after parameters that are considered the main subject of the function.
out-params come last (but I suspect some people follow the reverse)
To some extent it doesn't really matter -- namely the extent to which your users have IDEs that tell them the parameter order as they type the function name.
Can you suggest a precise definition for a 'value' within the context of programming without reference to specific encoding techniques or particular languages or architectures?
[Previous question text, for discussion reference: "What is value in programming? How to define this word precisely?"]
I just happened to be glancing through Pierce's "Types and Programming Languages" - he slips a reasonably precise definition of "value" in a programming context into the text:
[...] defines a subset of terms, called values, that are possible final results of evaluation
This seems like a rather tidy definition - i.e., we take the set of all possible terms, and the ones that can possibly be left over after all evaluation has taken place are values.
Based on the ongoing comments about "bits" being an unacceptable definition, I think this one is a little better (although possibly still flawed):
A value is anything representable on a piece of possibly-infinite Turing machine tape.
Edit: I'm refining this some more.
A value is a member of the set of possible interpretations of any possibly-infinite sequence of symbols.
That is equivalent to the earlier definition based on Turing machine tape, but it actually generalises better.
Here, I'll take a shot: A value is a piece of stored information (in the information-theoretical sense) that can be manipulated by the computer.
(I won't say that a value has meaning; a random number in a register may have no meaning, but it's still a value.)
In short, a value is some assigned meaning to a variable (the object containing the value)
For example type=boolean; name=help; variable=a storage location; value=what is stored in that location;
Further break down:
X = 2; where X is a variable while 2 is the value stored in X.
Have you checked the article in wikipedia?
In computer science, a value is a sequence of bits that is interpreted according to some data type. It is possible for the same sequence of bits to have different values, depending on the type used to interpret its meaning. For instance, the value could be an integer or floating point value, or a string.
Read the Wiki
Value = Value is what we call the "contents" that was stored in the variable
Variables = containers for storing data values
Example: Think of a folder named "Movies"(Variables) and inside of it are it contents which are namely; Pirates of the Carribean, Fantastic Beast, and Lala land, (this in turn is what we now call it's Values )