Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.
Concept
Bag-of-words model
Summary
The bag-of-words model is a simplifying representation used in natural language processing and information retrieval (IR). In this model, a text (such as a sentence or a document) is represented as the bag (multiset) of its words, disregarding grammar and even word order but keeping multiplicity. The bag-of-words model has also been used for computer vision.
The bag-of-words model is commonly used in methods of document classification where the (frequency of) occurrence of each word is used as a feature for training a classifier.
An early reference to "bag of words" in a linguistic context can be found in Zellig Harris's 1954 article on Distributional Structure.
The Bag-of-words model is one example of a Vector space model.
The following models a text document using bag-of-words. Here are two simple text documents:
(1) John likes to watch movies. Mary likes movies too.
(2) Mary also likes to watch football games.
Based on these two text documents, a list is constructed as follows for each document:
"John","likes","to","watch","movies","Mary","likes","movies","too"
"Mary","also","likes","to","watch","football","games"
Representing each bag-of-words as a JSON object, and attributing to the respective JavaScript variable:
BoW1 = {"John":1,"likes":2,"to":1,"watch":1,"movies":2,"Mary":1,"too":1};
BoW2 = {"Mary":1,"also":1,"likes":1,"to":1,"watch":1,"football":1,"games":1};
Each key is the word, and each value is the number of occurrences of that word in the given text document.
The order of elements is free, so, for example {"too":1,"Mary":1,"movies":2,"John":1,"watch":1,"likes":2,"to":1} is also equivalent to BoW1. It is also what we expect from a strict JSON object representation.
Note: if another document is like a union of these two,
(3) John likes to watch movies. Mary likes movies too. Mary also likes to watch football games.
its JavaScript representation will be:
BoW3 = {"John":1,"likes":3,"to":2,"watch":2,"movies":2,"Mary":2,"too":1,"also":1,"football":1,"games":1};
So, as we see in the bag algebra, the "union" of two documents in the bags-of-words representation is, formally, the disjoint union, summing the multiplicities of each element.
Official source
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.