ML Work-Flow (Part 3) - Feature Extraction

In this post, I'll talk about the details of Feature Extraction (aka Feature Construction, Feature Aggregation …) in the path of successful ML. Finding good feature representations is a domain related process and it has an important influence on your final results. Even if you keep all the settings same, with different Feature Extraction methods you would observe drastically different results at the end. Therefore, choosing the correct Feature Extraction methodology requires painstaking work.

Feature Extraction is a process of conveying the given raw data into set of instance points embedded in a standardized, distinctive and machine understandable space. Standardized means comparable representations with same length; so you can compute similarities or differences of the instances that have initially very versatile structural differences (like different length documents). Distinctive means having different feature values for different class instances so that we can observe clusters of different classes in the new data space. Machine understandable representation is mostly the numerical representation of the given instances. You can understand any document by reading it but machines only understand semantics implied by the numbers. Continue reading

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ML WORK-FLOW (Part2) - Data Preprocessing

I try to keep my promised schedule on as much as possible. Here is the detailed the first step discussion of my proposed Machine Learning Work-Flow, that is Data Preprocessing.

Data Preprocessing is an important step in which mostly aims to improve raw data quality before you dwell into the technical concerns. Even-though this step involves very easy tasks to do, without this, you might observe very false or even freaking results at the end.

I also stated at the work-flow that, Data Preprocessing is statistical job other than ML. By saying this, Data Preprocessing demands good data inference and analysis just before any possible decision you made. These components are not the subjects of a ML course but are for a Statistics. Hence, if you aim to be cannier at ML as a whole, do not ignore statistics.

We can divide Data Preprocessing into 5 different headings;

  1. Data Integration
  2. Data Cleaning
  3. Data Transformation
  4. Data Discretization
  5. Data Reduction

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Machine Learning Work-Flow (Part 1)

So far, I am planning to write a serie of posts explaining a basic Machine Learning work-flow (mostly supervised). In this post, my target is to propose the bird-eye view, as I'll dwell into details at the latter posts explaining each of the components in detail. I decide to write this serie due to two reasons; the first reason is self-education -to get all my bits and pieces together after a period of theoretical research and industrial practice- the second is to present a naive guide to beginners and enthusiasts.

Below, we have the overview of the proposed work-flow. We have a color code indicating bases. Each box has a color tone from YELLOW to RED. The yellower the box, the more this component relies on Statistics knowledge base. As the box turns into red[gets darker], the component depends more heavily on Machine Learning knowledge base. By saying this, I also imply that, without good statistical understanding, we are not able to construct a convenient machine learning pipeline. As a footnote, this schema is changed by post-modernism of Representation Learning algorithms and I'll touch this at the latter posts.

 

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Why I chose industry over academy

In general, if I need to choose something over some other thing I enlist the positive and negative facts about options and have a basic summation to find out the correct one.

Here I itemize my subjective pros and cons list. Maybe you might find it skewed or ridiculous but these are based on my 3 years of hard core academic effort and 2 years in industry (sum of my partial efforts). I think they present at least some of the obstacles you would see in the both worlds.

 

First, I start with the academy;

Pros--

  1. Academic life is the best in terms of freedom at work. You choose your study topic, at least to some extent, you team-up and follow the boundaries of human knowledge so as to extend it a bit. This is a very respectful and curious search. For sure, it is better than having a boss choosing your way to go. However , even this freedom is limited as in  the below comic :)
  2. Dresscode. Yes, academy is not so certain to define a particular dresscode for you, in most cases. You are free to put on your comfortable shorts and flip-flops and go to your office to work. However, it should be pointed out that present industry also realized the idiocy of strict dresscodes and it provides better conditions for the employees as well. Yet, business is still not comparable with the academy.2345
  3. Travel around the world with conferences, summer-schools, meetings, internships at low-cost. Meet people around the globe and feel the international sense.
  4. Respectful job. It urges the sense of respect as you say you are an academic and  people usually assume you are more intelligent than the most, thanks to great scientist ancestors.
  5. Set your schedule. Schedule of an academic is more flexible and you have a bit of freedom to define your work time.
  6. Teaching. It is really great to envision young people with your knowledge and experience. Even-more, it is a vital role in a society since you are able to shape the future with the young people you touch.
  7. Elegant social circle. Being an academic chains you with a social circle of people with a similar education level and supposedly similar level of cultivation. That of course does not mean that the industry consists of the ignorant but living in corporate life is more susceptible to facing unfortunate minds.

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I presented my Master Dissertation?

I am glad to be presented my master dissertation at the end, I collect valuable feedback from my community. Before, I shared what I have done so far for the thesis on the different posts. CMAP (Concept Map) and FAME (Face Association through Model Evolution) (I called it AME at the Thesis for being more generic) are basically two different method for mining visual concepts from noisy image sources such as Google Image Search or Flickr. You might prefer to look at the posts for details or I posted here also the presentation for the brief view of my work.

 

 

FAME: Face Association through Model Evolution

Here, I summarize a new method called FAME for learning Face Models from noisy set of web images. I am studying this for my MS Thesis. To be a little intro to my thesis, the title is "Mining Web Images for Concept Learning" and it introduces two new methods for automatic learning of visual concepts from noisy web images. First proposed method is FAME and the other work was presented here before, that is namely ConceptMap and it is accepted for ECCV14 (self promotion :)).

Before I start, I should disclaim that FAME is not a fully furnished work and waiting your valuable comments. Please leave your statements about anything you find useful, ridiculous, awkward or great.

In this work, we grasp the problem of learning face models for public faces from images collected from web through querying a particular person name. Collected images are called weakly-labelled by the rough prescription of defined query. However, the data is very noisy even after face detection, with false detections or several irrelevant faces Continue reading

Our ECCV2014 work "ConceptMap: Mining noisy web data for concept learning"

---- I am living the joy of seeing my paper title on the list of accepted ECCV14 papers :). Seeing the outcome of your work makes worthwhile all your day to night efforts, REALLY!!!. Before start, I shall thank to my supervisor Pinar Duygulu for her great guidance.----

In this post, I would like to summarize the title work since I believe sometimes a friendly blog post might be more expressive than a solid scientific article.

"ConceptMap: Mining noisy web data for concept learning" proposes a pipeline so as to learn wide range of visual concepts by only defining a query to a image search engine. The idea is to query a concept at the service and download a huge bunch of images. Cluster images as removing the irrelevant instances. Learn a model from each of the clusters. At the end, each concept is represented by the ensemble of these classifiers. Continue reading

Large data really helps for Object Detection ?

I stumbled upon a interesting BMVC 2012 paper (Do We Need More Training Data or Better Models for Object Detection? -- Zhu, Xiangxin, Vondrick, Carl, Ramanan, Deva, Fowlkes, Charless). It is claming something contrary to current notion of big data theory that advocates benefit of large data-sets so as to learn better models with increasing training data size. Nevertheless, the paper states that large training data is not that much helpful for learning better models, indeed more data is maleficent without careful tuning of your system !! Continue reading