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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Information System of Catering Selection by Using Clustering Analysis</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Boyko[</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Khrystyn</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>khovsk</string-name>
          <email>kristin.shakhovska@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Lviv Polytechnic National University</institution>
          ,
          <addr-line>Lviv79013</addr-line>
          ,
          <institution>Ukraine Linnaeus University</institution>
          ,
          <addr-line>Växjö</addr-line>
          ,
          <country country="SE">Sweden</country>
        </aff>
      </contrib-group>
      <fpage>0000</fpage>
      <lpage>0002</lpage>
      <abstract>
        <p>The topic of tourism is up-to-date because everyone wants to broaden their mind. An integral part of all trips is food, the difference is only in price and quality. Moreover, today is popular gastronomic tourism. The features of tourism are explored by using geodata analysis, numerical and categorical values. Catering are grouped by certain criteria. Data analysis using RStudio and Tableau is performed. An information system for catering selection is created. A correlation and regression analysis was performed on the analyzed data. The k-means algorithm for the analyzed nutrition data has been implemented. A system of four clusters for the selection of a catering facility was constructed.</p>
      </abstract>
      <kwd-group>
        <kwd>regression analysis</kwd>
        <kwd>clustering</kwd>
        <kwd>k-means algorithm</kwd>
        <kwd>system</kwd>
        <kwd>tourism</kwd>
        <kwd>nutrition</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>With the development of market economy and integration of the world economy the
role and place of the restaurant business were reviewed. Changes in economic
development in the country require the application of new approaches to management and
organization of activities, which should be aimed at maximizing consumer demand
and ensuring a high level of efficiency of their productive and economic activity.</p>
      <p>
        Not all modern selection systems take into account given parameters. Another
important factor is the price range of the restaurant and reliable reviews of it. After all,
the proposed parameters affect the accuracy of the characteristics of the desired
catering [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ].
      </p>
      <p>There are many geographic information systems, which in most cases are useful by
using them in the process of performing application tasks. Each tourist IS along with
the input and output modules contains a tools for performing spatial analysis
functions and performing specific user tasks. These tools directly depend on the data
models that are supported by a particular tourist IS and used for the user's tasks.</p>
      <p>
        Quite often, there is a need to predict new trends in the structure of catering, taking
into account a variety of factors - environmental, geopolitical, and situational. For
most formalized information solutions to existing IS and are reduced to the execution
of ready-made solutions provided by mapping tools. In authors opinion, the tools
should cover actions from a simple revision of existing catering facilities and the
implementation of auxiliary mapping supplements to the issuance of expert gastronomic
recommendations [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ].
      </p>
      <p>Consequently, the research area described above is interesting for research because
it contains many parameters that can be analyzed. It allows to build appropriate
relationships between data to form an effective solution. It is also necessary to group
catering facilities according to certain criteria.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Review of the Literature</title>
      <p>
        A large number of scientists [
        <xref ref-type="bibr" rid="ref15 ref16 ref17 ref18 ref19 ref20">15-20</xref>
        ] describe well-known clustering algorithms in
their work and propose their own methods of its application. But most of them cannot
provide an effective estimate, as we have a dynamic location database that can be
clearly defined as a knowledge base. The point is that with any known operations with
attributes, records, etc., there is no need for checking the relations that were created at
the beginning of the database creation. The constant accumulation of dynamic data
can lead to the restructuring of the knowledge base structure.
      </p>
      <p>
        Some researchers [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] propose universal multi-parameter clustering methods.
However, they contain limited tools for determining spatial models, since spatial real
dimensions contain real indicators.
      </p>
      <p>
        Some scientists have focused their research on spatial data. For example, various
statistical approaches have been included in the technique [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], elements of analytical
geometry have been used in the Delaunay triangulation analysis [
        <xref ref-type="bibr" rid="ref3 ref4">3, 4</xref>
        ], and the
method of density change in the distribution of random variables has been applied [
        <xref ref-type="bibr" rid="ref7 ref8">7, 8</xref>
        ]
and so on.
      </p>
      <p>
        This paper provides well-known clustering methods such as: CLIQUE [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ],
ENCLUS [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ], ORCLUS [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] and DOC [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]. However, the complexity of the method
calculations is that they find clusters and fine-tune the properties of certain objects
under predefined clustering algorithms. Cluster objects are identified by several
subjective parameters of the clustering algorithm. For example, in CLIQUE to perform
the analysis, it is necessary to determine the value of the interval ξ and the threshold
density τ. For ORCLUS it is necessary to determine in advance the number of clusters
k and the dimension of the subspaces p. For a DOC, a certain length w, the density
threshold α and an equilibrium coefficient β is required over a specified period. The
described parameters are determinative and necessary for the condition of passing the
clustering algorithm [
        <xref ref-type="bibr" rid="ref1 ref16 ref17 ref18 ref19">1, 16-19</xref>
        ].
      </p>
      <p>There is another issue that occurs when you use the specified clustering algorithm.
Namely, it is difficult to implement hierarchical clustering in each subspace, because
it requires the adaptation of certain applications and models. It is complex for the user
of this algorithm to perform many iterations to find the complete data set.</p>
      <p>
        Therefore, the paper proposes the ICEAGE method [
        <xref ref-type="bibr" rid="ref17 ref5">5, 17</xref>
        ], which is effective for
hierarchical spatial clustering (for two-dimensional spatial points). It is interactive and
allows you to achieve complexity O (n log n).
      </p>
    </sec>
    <sec id="sec-3">
      <title>Problem statement</title>
      <p>Nowadays, the topic of tourism is quite relevant, since everyone wants to broaden
their minds and satisfy their gastronomic demands. Indeed, an integral part of all
travel is a meal, a difference only in price and quality.</p>
      <p>The purpose of the article is to develop improve the efficiency of the catering
process and developing the information system for selecting catering by using improved
method of clustering based on the analysis of geodata, numeric and categorical
values. In the analysis, we will use two tools for analysis: RStudio and Tableau. To
achieve the goal, the authors put certain tasks in order:
1. To get acquainted with the means of analysis of R and Tableau.
2. Consider the probable relationship between data.
3. Identify key criteria for finding gastronomic solutions.
4. Split data into clusters.
5. To supplement the general system for finding food establishments.
3</p>
    </sec>
    <sec id="sec-4">
      <title>Materials and Methods</title>
      <p>
        Tableau uses the k-means method with a dispersion-based distribution method, thus
ensuring consistency between cycles. This goes through automatic pre-processing
steps to reduce the cost of data preparation that is required for this type of analysis.
These include the standardization of input parameters that automatically scalable data
and multidimensional match analysis [
        <xref ref-type="bibr" rid="ref1 ref10 ref11 ref12 ref13 ref14 ref15 ref2 ref3 ref4 ref5 ref6 ref7 ref8 ref9">1-15</xref>
        ].
      </p>
      <p>The K-means method in this study requires the initial specification of cluster
centers. So, the analysis begins with one defined classter, which selects variables and
calculates an arithmetic mean that is the threshold for splitting the data in half.</p>
      <p>
        In the process of separation, centroids are used to initialize K-means. This allows
to optimize the distribution of clusters. The next step is to select one of the two
clusters for the splitting operation. Again, the previous algorithm is repeated, i.e.: there is
a threshold for splitting the cluster in half. The clusters resulting from the splitting are
initialized by the centroids of the two parts of the split cluster and the centroid of the
central cluster. The algorithm is repeated until it reaches the set number of clusters
[
        <xref ref-type="bibr" rid="ref18">18</xref>
        ].
      </p>
      <p>
        In the process of analysis there is a large amount of multivariable data that need to
be processed [
        <xref ref-type="bibr" rid="ref19 ref20">19-20</xref>
        ]. For this purpose, we apply the Lloyd's algorithm, by which we
determine the square of the Euclidean distance for the calculation of clusters formed
during the disengagement process. Their collaboration allows us to determine the
initial centers for each k&gt; 1. It is known that the result of our analysis is directly
dependent on the number of clusters, so the resulting clustering is deterministic.
To analyze the data in Tableau, we use the Calinski-Harabasz criterion, which
determines the quality of the clusters. The Calinski-Harabasz criterion can be defined as:
SS
SSW
      </p>
      <p>B 
( N  k )
(k  1)
,
(1)
where SSB is the total variance between clusters; SSW - total dispersion within the
cluster; k is the number of clusters; N is the number of views.</p>
      <p>The value of the Calinski-Harabasz criterion indicates the cluster density. It means
that the higher the value of this criterion, the denser the clusters are located (the low
dispersion within the cluster), and the lower the cluster distance, the greater the
difference between the clusters.</p>
      <p>Since the Kalinsky-Harabash index is uncertain for k = 1, it cannot be used to
detect instances of creating a single cluster.</p>
      <p>Typically, clustering aims to highlight multiple groups of objects with similar
characteristics within a group, and between groups - they are different. The
peculiarity of co-clustering is the grouping of not only objects, but also the characteristics of
these objects themselves. That is, if the data is presented in the form of a matrix, then
clustering is a regrouping of the rows or columns of the matrix, and the
coclusterization is a re-grouping of the rows and columns of the data matrix.</p>
      <p>
        In the process of analysis, the authors propose the use of cluster accumulation
method. It is based on tools that allow you to divide the map into squares of a given
size. Grouping by certain features of certain objects occurs in each square of the map.
They also create clusters according to the algorithm described above. The process of
splitting clusters takes place until all markers are included in the closest cluster grids
[
        <xref ref-type="bibr" rid="ref17">17</xref>
        ].
      </p>
      <p>If in the process of analysis it is found that some marker is located within several
existing clusters, then by the algorithm of the method described above, the distance
from each cluster to it is determined. Accordingly, the marker is then added to the
closest, closest, cluster, using the fuzzy K-mean approach:
1) Initialization is carried out by accidental filling of matrix of the F with
preservaс
і0  ki  1
, returns to step 1 or accidentally
tion in the conditions of normalization
fills cluster centroids Vi .</p>
      <p>2) For each iteration we calculate:</p>
      <p>M
 kmi * X k
Vi  k 1 M
 kmi
k 1
, i  1, c</p>
      <p>,
Dki </p>
      <p>X k Vi
2 , k  1, M ,i  1, c
(3)
 kmi 
At the end of each iteration, the state of achieving accuracy is checking
 ki   k*i  
max
k 1,M ,i 1,c
,
where  k*i is the value that was calculated on the previous iteration.</p>
      <p>The result of such clustering is a list of tourist facilities with geodata and roads.
(4)
(5)</p>
    </sec>
    <sec id="sec-5">
      <title>Experiment</title>
      <p>
        In order to conduct research and analysis, you need to receive complete, updated
information on tourist sites. To do this, we will use the Google Maps API, which has
access to Google Maps websites and has a complete set of tools for determining
geographic parameters [
        <xref ref-type="bibr" rid="ref12 ref9">9, 12</xref>
        ].
      </p>
      <p>
        For analysis is convenient to use MongoDB, with the type of database NoSQL.
JSON should be used for describing and storing documents because it is open source
and required for use on different platforms [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ].
      </p>
      <p>The coordinates of the submitted tourist sites are provided in vector format and
described in GeoJSON format.</p>
      <p>The data is from kaggle.com, where they are open source. Authors provide
certain nutrition characteristics: Id, Name, Cuisine Style, Ranking, Rating, Price Range,
NumberofReviews, Reviews, URL_TA, ID_TA. They are presented in Error!
Reference source not found..
`
4</p>
      <p>For further analysis, the we used only: Title, City, Rating, Price, Number of
reviews. Preprocessing the data by the authors is done in Rstudio. The results are
similar to those that are analyzed in everyday life by users: the better the quality, the
higher the price. Further analysis by authors was carried out in the Tableau environment.
To do this, you must first transform data. The Price.Range text field should be
converted to numeric Price by replacing $ -&gt; 1, $$ - $$$ -&gt; 2, $$$$ -&gt; 3 (data
categorization) (Fig. 2).</p>
      <p>Thanks to the generated table on Fig. 3 you can pick up a meal for your needs.
For example, in order to choose the catering with the cheapest price range (price = 1)
and with the best rated catering (rating = 5), you can check the table by using a table
to check if this type is available in a user-defined city. The example is Barcelona with
a price range (price = 1), and with a rating of the catering (rating = 4) (Fig. 3).</p>
      <p>In order to verify that the user's assumptions about the place are accurate, you can
view requests with reviews (Fig. 4 and Fig. 5).
First of all, we find direct relations between parameters using the language R.
lm1 &lt;- lm(Rating ~ Number.of.Reviews, data = data_restaurants)
qqnorm(lm1$residuals, col="orange", pch=20)
qqline(lm1$residuals, col = "blue") (Fig. 6)
model1=rpart(Rating ~ Price.Range, data=data_restaurant3)
p = predict(model1, data_restaurant3)
plot(model1) (Fig. 7).</p>
      <p>The next step is calculation of the determination coefficient for linear regression
models.</p>
      <p>According to the results of the experiment, the determination coefficient is too
small and the linear regression for the data set selected by the authors is not
appropriate.</p>
      <p>
        We selected a polynomial regression model that exactly matches the study
described above:
I(Number_of_reviewers^4)+ I(Number_of_reviewers^5), data =
data_restaurants6)
&gt;summary(lmpoly)$r.squared
[
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] 0.05857986
      </p>
      <p>In this experiment, as in the previous ratio is too small. In parallel, the authors
make clustering of data according to the given parameters.</p>
      <p>According to the results of regression analysis, researchers have chosen two
methods of splitting into clusters: first, according to the number of reviews; and
secondly, in the price range. The results of clustering on the number of feedbacks are
shown on Fig. 8, where the orange circles are marked by the cities with the most
reviews. This color indicates the most accurate information with a range of values 1 537
453 – 2 136 471.</p>
      <p>The red color is marked with somewhat fewer reviews, with a range of values
ranging from 810,267 to 1,020,548. The smallest number of reviews is indicated by
blue, with values from 41,434 to 455,280.</p>
      <p>On fig.9 is shown system of cluster, which is based on price criteria. Different
types of clusters differ by colors:
 Red (1,609 – 1,722)
 Blue (1,735 – 1,807)
 Orange (1,829 – 1,916)
 Light blue (1,933 – 2,042)
 Green – noise data.</p>
      <p>By way of overlaying two types of clustering, we received four finite clusters.
The following tables 1-4 show detailed information about each of the clusters.</p>
      <p>Table 1 demonstrates input data, particularly, which variables we use and
clustering details.
The paper represents the several methods of analysis usage, namely regression and
clustering, for catering selection. The system can be used for Big data processing. The
results of analysis have shown that the criteria do not have a direct relationship
between each other (the correlation coefficient is very small), but data grouping and
clustering gives the opportunity to form a proper description of the catering.
Accordingly, for better perception, data was visualized in Tableau. As a result of the study,
the authors received an information system of clusters, through which you can define
a meal on the gastronomic criteria of the user and find out how accurate are the
reviews about it. Also associative rules can be used for analysis.</p>
    </sec>
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