I am new to Artificial Neural Networks.
I am interested in an application like this:
I have a significantly large set of objects. Each object has six properties, denoted by P1–P6. Each property has a value which is a symbolic value. In other words, in my example P1–P6 can have a value from the set {A, B, C, D, E, F}. They are not numeric. (Suppose A,B,C,D,E,F are colours; then you will understand my idea.)
Now, there is another property R that I am interested in. Suppose
R = {G1, G2, G3, G4, G5}
I need to train a system for a large set of P1–P6 and the relevant R. Now I want to do the following.
I have an object and I know the values of P1 to P6. I need to find
the R (The Group that the object belongs.)
To get a desired R what is the pattern I need to have in P1–P6.
As an example given that R = G2 I need to figure out any pattern in P1–P6.
My questions are:
What are the theories/technologies/techniques I should read and
learn in order to implement 1 and 2, respectively?
What are the tools/libraries you can recommend to get this
simulated/implemented/tested?
The way you described your problem, you need to look up various machine learning techniques. If it were me, I would try and read about k-NN (k Nearest Neighbours) for the classification. When I say classification, I mean getting the R if you know P1-P6. It is a really simple technique and should be helpful here.
As for the other way around, what you basically need is a representative sample of your population. This is I think not so usual, but you could try something like a k-means Clustering. Clustering methods usually determine the class of an object (property R) by themselves, but k-means Clustering is cool in this situation because you need to give it the number of object classes (e.g. different possible values of R), and in the end you get one representative sample.
You definitely shouldn't go for any really complex techniques (like neural networks) in my opinion since your data doesn't have a precise numerical interpretation and the values can't be interpreted gradually.
The recommended tools really depend on your base programming language. There's a great tool called Orange which is Python-based and it's my tool of choice for these kind of things (especially since it is really easy to connect your Python modules with C/C++). If you prefer Java, there's a quite similar tool called Weka that you could use. I think Weka is a little bit better documented, but I don't like Java so I've never tried it out.
Both of these tools have a graphical clickable interface where you could just load your data and get the classification done, play with the parameters and check what kind of output you get using different techniques and different set-ups. Once you decide that you got the results you need (or if you just don't like graphical interfaces) you can also use both of them as libraries of a kind when programming (Python for Orange and Java for Weka) and make the classification a part of a bigger project.
If you look through the documentation of Orange or Weka, I think it will give you a few ideas about what you could actually do with the data you have and when you know a few techniques that seem interesting to you and applicable to the data, maybe you could get more quality comments and info on a few specific methods here than when just searching for a general advice.
You should check out classification algorithms (a subsection of artificial intelligence), especially the nearest neighbor-algorithms. Your problem may be solved by different techniques, which all have different advantages and disadvantages.
However, I do not know of any method in artificial intelligence, which allows a two-way classification (or in other words, that both implement your prerequisites 1 and 2 simultaneously). As all you want to do so far is having a bidirectional mapping of P1..P6 <=> R, I would suggest to just use a mapping table instead of an artificial intelligence algorithm. An AI would work great if you not exactly know, which of your samples is categorized under A..E in P1..P6.
If you insist on using an AI for it, I'd suggest to first look at a Perceptron. A perceptron consists of input, intermediate and output neurons. For your example, you'd have the input-Neurons P1a..P1e, P2a..P2e, ... and five output neurons R1..R5. After training, you should be able to input P1..P6 and get the appropriate R1..R5 as output.
As for frameworks and technologies, I only know of the Business Intelligence suite for Visual Studio, although there are a lot of other frameworks for AI out there. Since I do not have used any of them (I always coded them myself in C/C++), I can't recommend any.
It seems like a typical classification problem. In case you really have a lot of data have a look at Apache Mahout which provides distributed implementations of machine learning algorithms. If you need something less complex for prototyping TimBL is a nice alternative.
Related
I have two confusions when I use machine learning algorithm. At first, I have to say that I just use it.
There are two categories A and B, if I want to pick as many as A from their mixture, what kind of algorithm should I use ( no need to consider the number of samples) . At first I thought it should be a classification algorithm. And I use for example boost decision tree in a package TMVA, but someone told me that BDT is a regression algorithm indeed.
I find when I have coarse data. If I analysis it ( do some combinations ...) before I throw it to BDT, the result is better than I throw the coarse data into BDT. Since the coarse data contains every information, why do I need analysis it myself?
Is you are not clear, please just add a comment. And hope you can give me any advise.
For 2, you have to perform some manipulation on data and feed it to perform better because from it is not built into algorithm to analyze. It only looks at data and classifies. The problem of analysis as you put it is called feature selection or feature engineering and it has to be done by hand (of course unless you are using some kind of technique that learns features eg. deep learning). In machine learning, it has been seen a lot of times that manipulated/engineered features perform better than raw features.
For 1, I think BDT can be used for regression as well as classification. This looks like a classification problem (to choose or not to choose). Hence you should use a classification algorithm
Are you sure ML is the approach for your problem? In case it is, some classification algorithms would be:
logistic regression, neural networks, support vector machines,desicion trees just to name a few.
TL;DR
I need help understanding some parts of a specific algorithm for structured data classification. I'm also open to suggestions for different algorithms for this purpose.
Hi all!
I'm currently working on a system involving classification of structured data (I'd prefer not to reveal anything more about it) for which I'm using a simple backpropagation through structure (BPTS) algorithm. I'm planning on modifying the code to make use of a GPU for an additional speed boost later, but at the moment I'm looking for better algorithms than BPTS that I could use.
I recently stumbled on this paper -> [1] and I was amazed by the results. I decided to give it a try, but I have some trouble understanding some parts of the algorithm, as its description is not very clear. I've already emailed some of the authors requesting clarification, but haven't heard from them yet, so, I'd really appreciate any insight you guys may have to offer.
The high-level description of the algorithm can be found in page 787. There, in Step 1, the authors randomize the network weights and also "Propagate the input attributes of each node through the data structure from frontier nodes to root forwardly and, hence, obtain the output of root node". My understanding is that Step 1 is never repeated, since it's the initialization step. The part I quote indicates that a one-time activation also takes place here. But, what item in the training dataset is used for this activation of the network? And is this activation really supposed to happen only once? For example, in the BPTS algorithm I'm using, for each item in the training dataset, a new neural network - whose topology depends on the current item (data structure) - is created on the fly and activated. Then, the error backpropagates, the weights are updated and saved, and the temporary neural network is destroyed.
Another thing that troubles me is Step 3b. There, the authors mention that they update the parameters {A, B, C, D} NT times, using equations (17), (30) and (34). My understanding is that NT denotes the number of items in the training dataset. But equations (17), (30) and (34) already involve ALL items in the training dataset, so, what's the point of solving them (specifically) NT times?
Yet another thing I failed to get is how exactly their algorithm takes into account the (possibly) different structure of each item in the training dataset. I know how this works in BPTS (I described it above), but it's very unclear to me how it works with their algorithm.
Okay, that's all for now. If anyone has any idea of what might be going on with this algorithm, I'd be very interested in hearing it (or rather, reading it). Also, if you are aware of other promising algorithms and / or network architectures (could long short term memory (LSTM) be of use here?) for structured data classification, please don't hesitate to post them.
Thanks in advance for any useful input!
[1] http://www.eie.polyu.edu.hk/~wcsiu/paper_store/Journal/2003/2003_J4-IEEETrans-ChoChiSiu&Tsoi.pdf
As stated in the title, I'm simply looking for algorithms or solutions one might use to take in the twitter firehose (or a portion of it) and
a) identify questions in general
b) for a question, identify questions that could be the same, with some degree of confidence
Thanks!
(A)
I would try to identify questions using machine learning and the Bag of Words model.
Create a labeled set of twits, and label each of them with a binary
flag: question or not question.
Extract the features from the training set. The features are traditionally words, but at least for any time I tried it - using bi-grams significantly improved the results. (3-grams were not helpful for my cases).
Build a classifier from the data. I usually found out SVM gives better performance then other classifiers, but you can use others as well - such as Naive Bayes or KNN (But you will probably need feature selection algorithm for these).
Now you can use your classifier to classify a tweet.1
(B)
This issue is referred in the world of Information-Retrieval as "duplicate detection" or "near-duplicate detection".
You can at least find questions which are very similar to each other using Semantic Interpretation, as described by Markovitch and Gabrilovich in their wonderful article Wikipedia-based Semantic Interpretation for Natural Language Processing. At the very least, it will help you identify if two questions are discussing the same issues (even though not identical).
The idea goes like this:
Use wikipedia to build a vector that represents its semantics, for a term t, the entry vector_t[i] is the tf-idf score of the term i as it co-appeared with the term t. The idea is described in details in the article. Reading the 3-4 first pages are enough to understand it. No need to read it all.2
For each tweet, construct a vector which is a function of the vectors of its terms. Compare between two vectors - and you can identify if two questions are discussing the same issues.
EDIT:
On 2nd thought, the BoW model is not a good fit here, since it ignores the position of terms. However, I believe if you add NLP processing for extracting feature (for examples, for each term, also denote if it is pre-subject or post-subject, and this was determined using NLP procssing), combining with Machine Learning will yield pretty good results.
(1) For evaluation of your classifier, you can use cross-validation, and check the expected accuracy.
(2) I know Evgeny Gabrilovich published the implemented algorithm they created as an open source project, just need to look for it.
I'm not sure if this is the best place to ask this, but you guys have been helpful with plenty of my CS homework in the past so I figure I'll give it a shot.
I'm looking for an algorithm to blindly combine several dependent variables into an index that produces the best linear fit with an external variable. Basically, it would combine the dependent variables using different mathematical operators, include or not include each one, etc. until an index is developed that best correlates with my external variable.
Has anyone seen/heard of something like this before? Even if you could point me in the right direction or to the right place to ask, I would appreciate it. Thanks.
Sounds like you're trying to do Multivariate Linear Regression or Multiple Regression. The simplest method (Read: less accurate) to do this is to individually compute the linear regression lines of each of the component variables and then do a weighted average of each of the lines. Beyond that I am afraid I will be of little help.
This appears to be simple linear regression using multiple explanatory variables. As the implication here is that you are using a computational approach you could do something as simple apply a linear model to your data using every possible combination of your explanatory variables that you have (whether you want to include interaction effects is your choice), choose a goodness of fit measure (R^2 being just one example) and use that to rank the fit of each model you fit?? The quality of a model is also somewhat subjective in many fields - you could reject a model containing 15 variables if it only moderately improves the fit over a far simpler model just containing 3 variables. If you have not read it already I don't doubt that you will find many useful suggestions in the following text :
Draper, N.R. and Smith, H. (1998).Applied Regression Analysis Wiley Series in Probability and Statistics
You might also try doing a google for the LASSO method of model selection.
The thing you're asking for is essentially the entirety of regression analysis.
this is what linear regression does, and this is a good portion of what "machine learning" does (machine learning is basically just a name for more complicated regression and classification algorithms). There are hundreds or thousands of different approaches with various tradeoffs, but the basic ones frequently work quite well.
If you want to learn more, the coursera course on machine learning is a great place to get a deeper understanding of this.
I have four sets of algorithms that I want to set up as modules but I need all algorithms executed at the same time within each module, I'm a complete noob and have no programming experience. I do however, know how to prove my models are decidable and have already done so (I know Applied Logic).
The models are sensory parsers. I know how to create the state-spaces for the modules but I don't know how to program driver access into ProLog for my web cam (I have a Toshiba Satellite Laptop with a built in web cam). I also don't know how to link the input from the web cam to the variables in the algorithms I've written. The variables I use, when combined and identified with functions, are set to identify unknown input using a probabilistic, database search for best match after a breadth first search. The parsers aren't holistic, which is why I want to run them either in parallel or as needed.
How should I go about this?
I also don't know how to link the
input from the web cam to the
variables in the algorithms I've
written.
I think the most common way for this is to use the machine learning approach: first calculate features from your video stream (like position of color blobs, optical flow, amount of green in image, whatever you like). Then you use supervised learning on labeled data to train models like HMMs, SVMs, ANNs to recognize the labels from the features. The labels are usually higher level things like faces, a smile or waving hands.
Depending on the nature of your "variables", they may already be covered on the feature-level, i.e. they can be computed from the data in a known way. If this is the case you can get away without training/learning.