I'm learning Machine Learning with Tensorflow. I've work with some dataset like Iris flower data and Boston House, but all those data's values was float.
Yes I'm looking for a dataset that contain data's values are in string format to practice. Can you give me some suggestions?
Thanks
I provide you just two easy-to-start places:
Tensorflow website has three very good tutorials to deal with word embedding, language modeling and sequence-to-sequence models. I don't have enough reputation to link them directly but you can easily find them here. They provide you with some tensorflow code to deal with human language
Moreover, if you want to build a model from scratch and you need only the dataset, try ntlk corpora. They are easy to download directly from the code.
Facebook's ParlAI project lists a good amount of datasets for Natural Language Processing tasks
IMDB's reviews dataset is also a classic example, also Amazon's reviews for sentiment analysis. If you take a look at kernels posted on Kaggle you'll get a lot of insights about the dataset and the task.
Related
I'm a newbie in the field of Machine Learning and Supervised learning.
My task is the following: from the name of a movie file on a disk, I'd like to retrieve some metadata about the file. I have no control on how the file is named, but it has a title and one or more additional info, like a release year, a resolution, actor names and so on.
Currently I have developed a rule heuristic-based system, where I split the name into tokens and try to understand what each word could represent, either alone or with adjacent ones. For detecting people names for example, I'm using a dataset of english names, and score the word as being a potential person's name if I find it in the dataset. If adjacent to it is a word that I scored as a potential surname, I score the two words as being an actor. And so on. It works with a decent accuracy, but changing heuristic scores manually to "teach" the system is tedious and unpredictable.
Such a rule-based system is hard to maintain or develop further, so, out of curiosity, I was exploring the field of machine learning. What I would like to know is:
Is there some kind of public literature about these kinds of problems?
Is ML a good way to approach the problem, given the limited data set available?
How would I proceed to debug or try to understand the results of such a machine? I already have problems with the "simplistic" heuristic engine I have developed..
Thanks, any advice would be appreciated.
You need to look into NLP (natural language processing). NLP deals with text processing and other things; for example entity recognition and tagging.
Here is an example of using Spacy library: https://spacy.io/usage/linguistic-features.
Some time ago I did a similar thing, you can see it here: https://github.com/Erlemar/Erlemar.github.io/blob/master/Notebooks/Fate_Zero_explore.ipynb
I am developing a website, which will recommend recipes to the visitors based on their data. I am collecting data from their profile, website activity and facebook.
Currently I have data like [username/userId, rating of recipes, age, gender, type(veg/Non veg), cuisine(Italian/Chinese.. etc.)]. With respect to above features I want to recommend new recipes which they have not visited.
I have implemented ALS (alternating least squares) spark algorithm. In this we have to prepare csv which contains [userId,RecipesId,Rating] columns. Then we have to train this data and create the model by adjusting parameters like lamdas, Rank, iteration. This model generated recommendation, using pyspark
model.recommendProducts(userId, numberOfRecommendations)
The ALS algorithm accepts only three features userId, RecipesId, Rating. I am unable to include more features (like type, cuisine, gender etc.) apart from which I have mentioned above (userId, RecipesId, Rating). I want to include those features, then train the model and generate recommendations.
Is there any other algorithm in which I can include above parameters and generate recommendation.
Any help would be appreciated, Thanks.
Yes, there are couple of others algorithms. For your case, I would suggest that you Naive Bayes algorithm.
https://en.wikipedia.org/wiki/Naive_Bayes_classifier
Since you are working on a web application, a JS solution, I guess, would come handy to you.
(simple) https://www.npmjs.com/package/bayes
or for example:
(a bit more powerful) https://www.npmjs.com/package/naivebayesclassifier
There are algorithms called recommender systems in machine learning. In this we have content based recommender systems. They are mainly used to recommend products/movies based on customer reviews. You can apply the same algorithm using customer reviews to recommend recipes. For better understanding of this algorithm refer this links:
https://www.youtube.com/watch?v=Bv6VkpvEeRw&list=PL0Smm0jPm9WcCsYvbhPCdizqNKps69W4Z&index=97
https://www.youtube.com/watch?v=2uxXPzm-7FY
You can go with powerful classification algorithms like
->SVM: works very well if you have more number of attributes.
->Logistic Regression: if you have huge data of customers.
You are looking for recommender systems using algorithms like collaborative filtering. I would suggest you to go through Prof.Andrew Ng's short videos on collaborative filtering algorithm and low-rank matrix factorization and also building recommender systems. They are a part of Coursera's Machine learning course offered by Stanford University.
The course link:
https://www.coursera.org/learn/machine-learning#%20
You can check week 9 for the content related to recommender systems.
I am trying to generate a Python program that determines if a website is harmful (porn etc.).
First, I made a Python web scraping program that counts the number of occurrences for each word.
result for harmful websites
It's a key value dictionary like
{ word : [ # occurrences in harmful websites, # of websites that contain these words] }.
Now I want my program to analyze the words from any websites to check if the website is safe or not. But I don't know which methods will suit to my data.
The key thing here is your training data. You need some sort of supervised learning technique where your training data consists of website's data itself (text document) and its label (harmful or safe).
You can certainly use the RNN but there also other natural language processing techniques and much faster ones.
Typically, you should use a proper vectorizer on your training data (think of each site page as a text document), for example tf-idf (but also other possibilities; if you use Python I would strongly suggest scikit that provides lots of useful machine learning techniques and mentioned sklearn.TfidfVectorizer is already within). The point is to vectorize your text document in enhanced way. Imagine for example the English word the how many times it typically exists in text? You need to think of biases such as these.
Once your training data is vectorized you can use for example stochastic gradient descent classifier and see how it performs on your test data (in machine learning terminology the test data means to simply take some new data example and test what your ML program outputs).
In either case you will need to experiment with above options. There are many nuances and you need to test your data and see where you achieve the best results (depending on ML algorithm settings, type of vectorizer, used ML technique itself and so on). For example Support Vector Machines are great choice when it comes to binary classifiers too. You may wanna play with that too and see if it performs better than SGD.
In any case, remember that you will need to obtain quality training data with labels (harmful vs. safe) and find the best fitting classifier. On your journey to find the best one you may also wanna use cross validation to determine how well your classifier behaves. Again, already contained in scikit-learn.
N.B. Don't forget about valid cases. For example there may be a completely safe online magazine where it only mentions the harmful topic in some article; it doesn't mean the website itself is harmful though.
Edit: As I think of it, if you don't have any experience with ML at all it could be useful to take any online course because despite the knowledge of API and libraries you will still need to know what it does and the math behind the curtain (at least roughly).
What you are trying to do is called sentiment classification and is usually done with recurrent neural networks (RNNs) or Long short-term memory networks (LSTMs). This is not an easy topic to start with machine learning. If you are new you should have a look into linear/logistic regression, SVMs and basic neural networks (MLPs) first. Otherwise it will be hard to understand what is going on.
That said: there are many libraries out there for constructing neural networks. Probably easiest to use is keras. While this library simplifies a lot of things immensely, it isn't just a magic box that makes gold from trash. You need to understand what happens under the hood to get good results. Here is an example of how you can perform sentiment classification on the IMDB dataset (basically determine whether a movie review is positive or not) with keras.
For people who have no experience in NLP or ML, I recommend using TFIDF vectorizer instead of using deep learning libraries. In short, it converts sentences to vector, taking each word in vocabulary to one dimension (degree is occurrence).
Then, you can calculate cosine similarity to resulting vector.
To improve performance, use stemming / lemmatizing / stopwords supported in NLTK libraires.
Dear all I am working on a project in which I have to categories research papers into their appropriate fields using titles of papers. For example if a phrase "computer network" occurs somewhere in then title then this paper should be tagged as related to the concept "computer network". I have 3 million titles of research papers. So I want to know how I should start. I have tried to use tf-idf but could not get actual results. Does someone know about a library to do this task easily? Kindly suggest one. I shall be thankful.
If you don't know categories in advance, than it's not classification, but instead clustering. Basically, you need to do following:
Select algorithm.
Select and extract features.
Apply algorithm to features.
Quite simple. You only need to choose combination of algorithm and features that fits your case best.
When talking about clustering, there are several popular choices. K-means is considered one of the best and has enormous number of implementations, even in libraries not specialized in ML. Another popular choice is Expectation-Maximization (EM) algorithm. Both of them, however, require initial guess about number of classes. If you can't predict number of classes even approximately, other algorithms - such as hierarchical clustering or DBSCAN - may work for you better (see discussion here).
As for features, words themselves normally work fine for clustering by topic. Just tokenize your text, normalize and vectorize words (see this if you don't know what it all means).
Some useful links:
Clustering text documents using k-means
NLTK clustering package
Statistical Machine Learning for Text Classification with scikit-learn and NLTK
Note: all links in this answer are about Python, since it has really powerful and convenient tools for this kind of tasks, but if you have another language of preference, you most probably will be able to find similar libraries for it too.
For Python, I would recommend NLTK (Natural Language Toolkit), as it has some great tools for converting your raw documents into features you can feed to a machine learning algorithm. For starting out, you can maybe try a simple word frequency model (bag of words) and later on move to more complex feature extraction methods (string kernels). You can start by using SVM's (Support Vector Machines) to classify the data using LibSVM (the best SVM package).
The fact, that you do not know the number of categories in advance, you could use a tool called OntoGen. The tool basically takes a set of texts, does some text mining, and tries to discover the clusters of documents. It is a semi-supervised tool, so you must guide the process a little, but it does wonders. The final product of the process is an ontology of topics.
I encourage you, to give it a try.
I want to teach myself enough machine learning so that I can, to begin with, understand enough to put to use available open source ML frameworks that will allow me to do things like:
Go through the HTML source of pages
from a certain site and "understand"
which sections form the content,
which the advertisements and which
form the metadata ( neither the
content, nor the ads - for eg. -
TOC, author bio etc )
Go through the HTML source of pages
from disparate sites and "classify"
whether the site belongs to a
predefined category or not ( list of
categories will be supplied
beforhand )1.
... similar classification tasks on
text and pages.
As you can see, my immediate requirements are to do with classification on disparate data sources and large amounts of data.
As far as my limited understanding goes, taking the neural net approach will take a lot of training and maintainance than putting SVMs to use?
I understand that SVMs are well suited to ( binary ) classification tasks like mine, and open source framworks like libSVM are fairly mature?
In that case, what subjects and topics
does a computer science graduate need
to learn right now, so that the above
requirements can be solved, putting
these frameworks to use?
I would like to stay away from Java, is possible, and I have no language preferences otherwise. I am willing to learn and put in as much effort as I possibly can.
My intent is not to write code from scratch, but, to begin with putting the various frameworks available to use ( I do not know enough to decide which though ), and I should be able to fix things should they go wrong.
Recommendations from you on learning specific portions of statistics and probability theory is nothing unexpected from my side, so say that if required!
I will modify this question if needed, depending on all your suggestions and feedback.
"Understanding" in machine learn is the equivalent of having a model. The model can be for example a collection of support vectors, the layout and weights of a neural network, a decision tree, or more. Which of these methods work best really depends on the subject you're learning from and on the quality of your training data.
In your case, learning from a collection of HTML sites, you will like to preprocess the data first, this step is also called "feature extraction". That is, you extract information out of the page you're looking at. This is a difficult step, because it requires domain knowledge and you'll have to extract useful information, or otherwise your classifiers will not be able to make good distinctions. Feature extraction will give you a dataset (a matrix with features for each row) from which you'll be able to create your model.
Generally in machine learning it is advised to also keep a "test set" that you do not train your models with, but that you will use at the end to decide on what is the best method. It is of extreme importance that you keep the test set hidden until the very end of your modeling step! The test data basically gives you a hint on the "generalization error" that your model is making. Any model with enough complexity and learning time tends to learn exactly the information that you train it with. Machine learners say that the model "overfits" the training data. Such overfitted models seem to appear good, but this is just memorization.
While software support for preprocessing data is very sparse and highly domain dependent, as adam mentioned Weka is a good free tool for applying different methods once you have your dataset. I would recommend reading several books. Vladimir Vapnik wrote "The Nature of Statistical Learning Theory", he is the inventor of SVMs. You should get familiar with the process of modeling, so a book on machine learning is definitely very useful. I also hope that some of the terminology might be helpful to you in finding your way around.
Seems like a pretty complicated task to me; step 2, classification, is "easy" but step 1 seems like a structure learning task. You might want to simplify it to classification on parts of HTML trees, maybe preselected by some heuristic.
The most widely used general machine learning library (freely) available is probably WEKA. They have a book that introduces some ML concepts and covers how to use their software. Unfortunately for you, it is written entirely in Java.
I am not really a Python person, but it would surprise me if there aren't also a lot of tools available for it as well.
For text-based classification right now Naive Bayes, Decision Trees (J48 in particular I think), and SVM approaches are giving the best results. However they are each more suited for slightly different applications. Off the top of my head I'm not sure which would suit you the best. With a tool like WEKA you could try all three approaches with some example data without writing a line of code and see for yourself.
I tend to shy away from Neural Networks simply because they can get very very complicated quickly. Then again, I haven't tried a large project with them mostly because they have that reputation in academia.
Probability and statistics knowledge is only required if you are using probabilistic algorithms (like Naive Bayes). SVMs are generally not used in a probabilistic manner.
From the sound of it, you may want to invest in an actual pattern classification textbook or take a class on it in order to find exactly what you are looking for. For custom/non-standard data sets it can be tricky to get good results without having a survey of existing techniques.
It seems to me that you are now entering machine learning field, so I'd really like to suggest to have a look at this book: not only it provides a deep and vast overview on the most common machine learning approaches and algorithms (and their variations) but it also provides a very good set of exercises and scientific paper links. All of this is wrapped in an insightful language starred with a minimal and yet useful compendium about statistics and probability