As we mentioned in the previous post, our team is working on a project to help you make decisions about buying different products and services. We try to help users create an objective view of the specific items they want to buy by analyzing published reviews of other users. Currently, we’ve downloaded enough reports and product articles in Czech and English language to analyze individual views. In the first phase it was necessary to adapt the obtained texts to the form suitable for analysis.

It was necessary to divide the documents into individual sentences, because users often present more ideas in one document and evaluate more criteria. The next step was to remove insignificant words that do not bring any or just little information value. For example, clutches, prepositions, web addresses, and so on. In this step, we also used our own POS analyzer, which assigns the words in sentence word types, and our own dataset with stop words. In particular, nouns, adjectives and verbs were interesting for us. Subsequently, we worded the words into their basic shapes, by specifying the roots of words.

We have transformed the edited documents into vector shape using tf-ifd and then split them into clusters with the same themes using k-means methods. We have managed to identify approximately diversified clusters with a high degree of internal integrity. Identified topics were related to the main parameters of the product segment surveyed.

The clusters created for the whole segment, based on expert articles, were then used to classify product reviews. From identified clusters for individual reviews, we chose those with the highest predictive value – and are presented as a suitable representative for a given set of reviews. The result of the analysis is shown in the example below.

Jan Přichystal

We will inform you about the milestones we have achieved in analyzing text reviews. Let’s take a look at our research.


Our team is currently working on a project to help make decisions about buying different products. A huge amount of opinions and reviews of individual products can be found on the Internet.
These user reviews are distributed across a variety of discussion forums, product rating sites, or specific portals. For a regular user, it’s difficult to find the information needed, get a look at them, and make its own opinion.


In order to analyze large amounts of unstructured data, we have decided to use machine learning methods. We want to use these data to identify topics that are important to users and to determine their positive or negative attitudes towards individual product features.

Current status

We are currently working on creating crawlers for downloading user reviews and articles about the selected product group. These crawlers are tailored to the structure of specific sites. Crawlers from these sites get relevant data that can help in analyzing themes and attitudes. So far, we have created eight crawlers, which have helped us to download about half a million user reviews and expert articles about two thousand products in two languages ​​(Czech and English).

Problems solved

We had to deal with several issues when acquiring the data. One of the main ones is the different way of labeling products on different sites. Although it is an identical product, there are differences in names that complicate product pairing. Another problem is limiting the number of accesses to some sites in the form of code captcha. The last issue that needs to be solved is the changing web structure that causes crawlers to fail.


We have a practically closed first phase of the project in which we have defined the task of creating data acquisition tools for subsequent analysis. In the next phase, using machine learning methods, we will work to uncover the topics discussed and attitudes of users.

Jan Přichystal