Developers Club geek daily blog

Data analysis of the weather station founded on Arduino

3 years, 6 months ago
Creation of own personal meteorological station became much simpler, than earlier. Taking into account non-constant weather in New England, we have decided that we want to create our own meteorological station and to use MATLAB for the analysis of meteodata.

In article we will answer the following questions:
  • In what direction the wind within the last 3 hours blew?
  • How temperature and dew point within the last week changed?
  • Whether on the business barometric pressure at thunder-storm approach falls?

It is clear that the considered questions are rather simple, but the described receptions and teams will help you to solve more complex practical challenges.

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Solar eclipses: from the past in the future, from Earth to Jupiter (the research conducted by means of Wolfram Language)

3 years, 6 months ago

To download article in the form of the CDF-file.
I express huge gratitude to Kirill Guzenko for the help in transfer.

Perhaps, you heard that on March 20 there was solar eclipse. The solar eclipse will be visible or not depends on in what point of the planet you are. If the solar eclipse is visible, it will be always possible to learn about it from mass media which usually create some sensation round this event? weather conditions at the time of eclipse, other parts are reported. If in place in which you are, the solar eclipse is not visible, most likely you even do not learn about it. However, often people from community Wolfram Community from all parts of the world? both experienced, and beginner developers, take part in discussion of similar things. And it is very healthy to observe how the knowledge of subject and the Wolfram technologies are transferred each other from people from all corners of Earth.

Not so long ago in community Wolfram Community five discussions in which the last solar eclipse was discussed have been created. They are given below in that order in which they appeared in community. Posts contain data on supervision of recent eclipse and their analysis, forecasts of future eclipses and it is a little how eclipses pass on other planets.

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3 years, 6 months ago

To download article in the form of the document Mathematica (NB), the CDF-file or PDF.
I express huge gratitude to Kirill Guzenko for the help in transfer.

In this article some properties of the figure known since ancient times called arbelos are systematically checked. It includes some new opening and the generalizations provided by the author of this work.


Have been motivated with computing advantages which Mathematica has, some time ago I have decided to start research of properties of arbelos? very interesting geometrical figure. Since then I have been impressed with large number of surprising opening and computing problems which arose because of all of the extending volume of the literature concerning this remarkable object. I remember its similarity to the lower part of the cult bicycle of penny farthing from The Prisoner (TV series of the 1960th), shutovsky cap of Pancha (the well-known Punch and Judy) and the yin-yan character with one inverted arc; see fig. 1. Now there is specialized directory of Archimedean circles (the circles containing in arbelosa) [1] and important use of properties of arbelos which lie out of field of mathematics and computing sciences [2].

Many famous researchers were engaged in this subject, including Archimedes (killed by the Roman soldier in 212 g BC), Pappus (320 g AD), Christian O. Mor (1835-1918), Victor Tebo (1882-1960), Leon Bankoff (1908-1997), Martin Gardner (1914-2010). For quite some time now Clayton Dodge, Peter Ai are engaged in properties of arbelos. Wu, Thomas Shokh, Hirosha Okumur, Masayuki Watanabe and other.

Leon Bankoff? the person who drew general attention to arbelos in the last 30 years. Shokh has drawn Benkoff's attention to arbelos in 1979, having opened some new Archimedean circles. It has sent 20-page hand-written work to Martin Gardner who has directed it to Benkoffu who then has sent 10-page fragment of the copy of the manuscript to Dodge in 1996. Because of death Benkoffa the planned collaboration has been interrupted until Dodge has reported about some new opening [3]. In 1999 Dodge has told that it will be required to him from five to ten years to sort all material which it locates, having spread out all this has put on piles. Now this work is still continued. It is not surprising that in the fourth volume The Art of Computer Programming, it is told that important work demands large number of time.

Fig. 1. Bicycle of penny farthing, Panch and Judee's doll, physical arbelos.

Arbelos (? shoemaker's knife? in Greek) it is called so because of the similarity to knife blade which is used shoemakers (Fig. 1). Arbelos? the flat area limited to three semi-circles and the general basic line (fig. 2). Archimedes probably was the first who has started studying mathematical properties of arbelos. These properties are described in theorems with the 4th on the 8th its books Liber assumptorum (or Books of lemmas). Perhaps, this work was written not by Archimedes. Doubts have appeared after transfer from Arab of the Book of lemmas in which Archimedes is mentioned repeatedly, but is told nothing about his authorship (however, there is opinion, what this book? fake [4]). The book of Lemmas also contains the well-known Archimedean Problema Bovinum [5].

This article is directed on systematic statement of some properties of arbelos and has no exhaustive character. Our purpose consists in developing uniform computing methodology to present these properties in format of the training article. All properties are built within certain sequence and provided with proofs. These proofs have been implemented by means of testing of the equivalent calculated statements. During execution of this work as the author some discoveries have been made and some generalizations are made.

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The detailed analysis of Habrakhabr by means of the Wolfram Language language (Mathematica)

3 years, 6 months ago

To download post in the form of the document Mathematica which contains all code used in article, together with additional files, it is possible here (archive, ~ 147 MB).

The analysis of social networks and various media resources is now quite popular direction and that it was more surprising to find out for me that on Habrakhabr, in fact, there are no articles which would contain the analysis of the large number of information (posts, key word, comments and so forth) which is saved up on it for quite big period of work.

I hope that this post will be able to interest many participants of Habrakhabr. I will be glad to sentences and ideas of the possible further directions of development of this post, and also any notes and recommendations.

In post articles relating to hubs will be considered, all 62000 articles from 264 hubs participated in the analysis. Articles written only for corporate blogs of the companies in post were not considered, and also the posts which have not got to group were not considered? the interesting?.

In view of the fact that the database constructed in post formed for some time before the publication, namely on April 26, 2015, the posts published on Habrakhabr after this date (and also, perhaps, new hubs) in this post were not considered.

Table of contents

Import of the list of hubs
Import of links to all articles of Habrakhabr
Import of all articles of Habrakhabr
Functions of extraction of specific data from character XML representation of post
Creation of database of posts of Habrakhabr by means of Dataset
Results of data handling
? Short analysis of hubs
? Bond graph of hubs on Habrakhabr
? Number of articles depending on time
? Number of images (video) used in posts depending on time
? Clouds of key word of Habrakhabr and separate hubs
? The sites to which refer in articles on Habrakhabr
? Codes which provide in articles on Habrakhabr
? Frequency of meeting of words
? Rating and numbers of viewings of posts, and also probability of achievement of their certain values
? Dependence of rating and number of viewings of post on publication time
? Dependence of rating of post on its volume

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Algorithm of Quickhull for finding of convex shell

3 years, 6 months ago
How definition, convex shell of some set says? this smallest convex set comprising set. Convex shell of finite set of in pairs different points is the polyhedron.
The STD function suits for implementation of one-dimensional case of algorithm of Quickhull:: minmax_element. It is possible to find set of implementations of algorithm of Quickhull for flat case in network. However, for case of any dimension to descent there is only one heavyweight implementation from the site

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DataTalks #2: Data visualization

3 years, 6 months ago
The second meeting of community DataTalks has been devoted to data visualization? to one of the most important and strong tools in hands of analysts. After all how results of research work are provided, solutions and the customer's outputs depend. In addition, visualization helps to carry out preliminary data analysis and quickly to find new interrelations.
Under cat you will find records of speeches of representatives of the companies Wargaming, Ambitious Suits Consulting, Targetprocess, A2 Consulting and the TUT.BY Internet portal. Speakers have shared experience of visual and informative data representation.
The meeting has traditionally taken place? under the tank?, at the main office of the SOOO company? Game Strim?, Minsk office of development of Wargaming.

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Gauges: whether it is worth using them for data visualization

3 years, 7 months ago

Data visualization — the effective way of information representation comprising large number of different tools. Gauges (scales, indicators) — one of types of such tools which is if not popular, then precisely often applied. But as far as such type of visualization is useful and whether it is worth using it?

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New in Wolfram Language: the TimelinePlot function for creation of time line

3 years, 7 months ago
A few years ago we have created the site devoted to chronology of emergence and development of the different systematized data and the calculated knowledge which you can look at online. I have written code which places events along time line, and then our designers have carried out serious work concerning design of the received material (fonts, headings, colors and so forth) and have brought quality to commercial level.

Generally, last year we have added the NumberLinePlot function to Wolfram Language for visualization of points, areas and inequalities. As soon as users have started working with NumberLinePlot, we have started receiving requests for introduction of similar function, but with dates and time therefore we have decided that time for TimelinePlot has come.

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Creation of full-fledged applications on Max 7. Part 1 — the Problem definition, visual programming

3 years, 7 months ago
At solution of problems of information visualization, obviously, there is question of practical implementation of the conceived. This cycle of articles is devoted to design process of applications by means of visual programming in Max 7 from the Cycling company '74. Let's begin studying of question, from simple to the difficult. Let's pass way from amateur preparation to full-fledged "one-file" application (standalone .exe).

Level: the easy

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We analyze attendance of employees according to SKUD

3 years, 7 months ago

To me, as well as to the majority reading this text to sit down in working chair, it is necessary to authenticate successfully itself in enterprise system of control of access (further SKUD). In each company it becomes differently: by means of electronic cards, biometrics, passwords, or in the old manner — with entering of your signing up by the security guard in paper log. It would seem, data of attendance already have storage and arrive there in one format, the logic of calculation of time is simple, as day but very few people use these data. In most cases the ordinary employee, even its administration often cannot answer number of the simple, but having practical value questions: how many hours I already am on workplace? Whether the employee Denisov came to office already today? Whether the citizen Frolova has returned after lunch? In which hour the employee Smirnov has the day before yesterday left work. In article I will tell how it is possible to receive answers to these questions and I will try to convince that accounting of time spent at office is useful to employees. If it became interesting — kindly I ask under kat.

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