ISKE 2012 International Conference, Beijing, 2012

1. Mobile Technologies and Biotechnology
Research Group (G-TeC)
Shop&Go: The Routing Problem
Applied to the
Shopping List on Smartphones
Inmaculada Pardines and Victoria Lopez

2. Contents topics
Routing
Problem
Algorithms
SVS-NVS
Functionalities
Simulations

3. Routing Problem
Shopping list
mobile technology

4. Routing Problem Shopping list
Nowadays, there are a lot of
applications that allow users to
carry out different tasks.
Smartphones have become
essential tool in our lives.
Lists
Search a Product
an
It is not only used to communicate
by a voice call or a SMS, but for
executing a great number of
applications such as:
games, music, e-mail, MMS, PDA,
digital photograph and digital video,
video call, Internet and even digital
television.

5. Motivation
In our working group, we develop mobile applications that try to make
people life easier with the aid of a mobile. The work presents in this
paper is focused in this idea.
We propose a new mobile tool which optimizes the route, and so on,
the time necessary to do the shopping in a supermarket.
There were some studies about this subject but not applied to mobiles.
Motivation
Moreover, there are Android applications related to the shopping list.
Some examples are Hungry!, Shoplist and ShopSavvy Barcode Scanner.
Some functionalities allows to write and to save the shopping
list, to organize the different products by colors and to send this list by
e-mail or SMS. Also to identify a barcode using the mobile camera and
to provide a price and store lists.
(Shop&Go)
also optimizes the
shopping route in a
supermarket and add
more functionalities

6. supermarket
Arquitecture
Data base of products (barcodes). Device (smarthphone)
Programming language Java (Eclipse – Galileo 3.5)
+ ADT plugin for Android 2.2
API Google Maps
SQLite database for Android
Contents Providers to share information between apps
PHP to manage the virtual (and free) database
Apache server, open code for Linux and windows, HTTP
protocol , SQL for relational data base,
www.000webhost.com (1500 MB free server)
Testing on HTC Desire with Android 2.1 Eclair, Samsung
Galaxy S II Android 2.3 Gingerbread, and tablet Archos 10
Android 2.2. between others.
BBDD
(Products)

7. Algorithms NVS - SVS
How to optimize you time at shopping

8. Algorithms SVS - NVS
This algorithm obtains the shortest path from an
origin vertex to every vertex of a graph with
nonnegative path costs.
It uses the Dijkstra matrix to find the shortest path to
go from a node to the next one.
cash registers
The idea is that the distance covered by the
customer to make the shopping is the shortest
if the products close to the cash registers are
taken as the last ones.
fruit
tomato
Start
Sorted Vertex Search Algorithm (SVS Algorithm)
Fig. 1. Route from the SVS
1. The S (Solution) set is initialized with the origin node 0.
2. The L (List) set is created by searching in a database which node is associated to each
product of the shopping list. It is necessary to include in the set the cash register
node. Then, these vertices are sorted from low to high.
3. This loop is executed until the L set is empty: the heuristic finds the shortest path
between the last node of S and the first node of L using the Dijkstra matrix. This node
of L is removed and the nodes that belong to this path are included in the S set.

9. Sorted Vertex Search Algorithm (SVS Algorithm)
tomato
Start
Algorithms SVS - NVS
Vertex
3
8
12
cash registers
Product
Tomato
Fruit
Chocolate
fruit
Table 1. Shopping list of Example 1.
Fig. 1. Route from the SVS
The heuristic starts from the sets: S={0} and L={3,8,12,18}, where the node 18
corresponds to the cash registers.
First, the shortest path between nodes 0 and 3 is searched. This path is through node 1,
so S={0,1,3}. Node 3 is removed from L. Then, the optimum path between nodes 3 and 8
is found through node 4. The process continues in this way until L is empty. Finally, the
Solution Set is S={0,1,3,4,8,9,10,12,18} and the obtained route is shown in Fig.1.

10. Algorithms SVS - NVS
Start
Nearest Vertex Search Algorithm (NVS Algorithm)
The decision to establish the optimum path in this
heuristic is based on the idea that the customer
moves always from a node to the closest one which
is related to a product of the shopping list.
cash registers
aubergine
The decision to establish the optimum path in this
heuristic is based on the idea that the customer
moves always from a node to the closest one which
is related to a product of the shopping list.
coffee
Fig. 2. Route from the NVS
1. The S set is initialized with the origin node 0.
2. The L set is created by searching in a database which node is associated to each
product of the shopping list. It is necessary to include in the set the cash register
node.
3. This loop is executed until the L set is empty: the distance from the current vertex to
every node of L is found. The node with the shortest distance is selected as the next
one to move. This node is included in the Solution set and removed from the List set.

11. Start
Algorithms SVS - NVS
Sorted Vertex Search Algorithm (SVS Algorithm)
Table 2. Shopping list of Example 2.
Vertex
16
Aubergines
9
Example 2 describe the heuristic. The shopping list is made
up of coffee and aubergines. The heuristic starts from the
sets: S={0} and L={16,9}.
In this case, the L elements are not numbering sorted; they
are saved as the product appears in the shopping list.
cash registers
Coffee
coffee
aubergine
Product
Fig. 2. Route from the NVS
Initially, the distance between node 0 and every node of L is calculated by using the distance between
shelves from the map provided by the supermarket. In our example node 0 is five meters apart from
node 16 and 13.5 meters apart from node 9. So, the heuristic selects vertex 16 as the next one to go,
adding it to the S set and removing it from L set. The Dijkstra matrix is used to calculate the minimum
path between two vertices. The selected node in the current iteration is used as the starting point of
the next one, calculating the distances from every node of L to it. The vertex with the low distance will
be the next one to move. The process continuous in this way until L is empty. When all the nodes of
the shopping list have been covered, the algorithm searches for the best path from the last node of S
to the cash registers. Finally, the Solution Set is S={0,17,16,6,7,9,10,12,18} and the obtained route is
shown in Fig.2.

12. Comparative between the SVS and the
NVS Algorithms
List of Example 3
Product
Salad
Rice
Fruit
Chocolates
Honey
Vertex
3
5
8
12
16
List of Example 4
Product
Cereals
Legumes
Tomatoes
Vertex
16
4
3
Applying the SVS algorithm to the example 3, the customer will have to pass the nodes
0, 1, 3, 2, 5, 8, 9, 10, 12, 11, 6, 16, 18, in this order. The total distance 36 meters.
For this example the NVS heuristic achieves a better solution with a total distance of
27.5 meters and a route which the vertices follows the order 0, 17, 16, 5, 8, 4, 3, 2, 6,
11, 12, 18.
However, for the example 4 the SVS heuristic achieves the best solution with a total
distance of 22 meters (S={0,1,3,4,5,16,18}) whereas the NVS algorithm obtains a path
of 24.5 meters long (S={0,17,16,2,3,4,5,16,18}).

13. Functionalities &
Simulation
How much we can do for you

14. More functionalities
» Muestre y cuente su presentación con Difundir presentación de diapositivas
» Search a product in the supermarket. The customer can select a product looking for
»
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»
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it in a shopping list or writing their name in the corresponding field. Then, the
application shows the product location pointing out in a map.
List creation and edition. Users can create lists, give then a name and add them a
description. The new lists will be permanent . Once they have been created, they
are saved for next searches in a new execution of the application in the future.
List removing. The user can remove an existing shopping list at any time.
Search the price of a product. After the customer selects the products of his
shopping list, the application shows the prices of all these products.
Send a shopping list by e-mail. Once a shopping list is created, it can be sent by email and another person can do the shopping.
Selection between two heuristics. The user can select between the solution offered
by the SVS heuristic and the solution achieved by the NVS algorithm. The routes
provided by this two heuristics are usually different. Then, it is the customer
according to his preferences who decides what route is going to select.
Display the route in a map. The user can see in a map the route which has to cover
to purchase all the products of a shopping list. Pressing a product after taking it,
removes it from the list.
Display the route in text. And voice routing (for people with visual discapacity)

15. Java packages &
classes

16. use
Use case diagram

18. Conclusions
A mobile application for shopping in an efficient way is presented in this paper.
Two heuristics have been proposed to find the shortest route for taking the products of a shopping list. We
have demonstrated that it is impossible to assure which heuristic is the best one.
Therefore, we have decided to include the two algorithms in the Shop&Go application.
Shop&Go app has also other functional requirements such as creating or deleting lists, searching for a product
price, locating a product in the supermarket map and so on. Several simulations that prove the high
performance of the proposed application are shown.
However, this application has a difficult marketing.
The idea of doing the shopping in a short time benefits the customers but it is opposed to the interest of the
supermarkets. These businesses frequently change the products layout to force the customer to go through
many corridors, increasing the probability that the customer buys more products than he needs.

19. Mobile Technologies and Biotechnology
Research Group (G-TeC)
Thank you very much!
Xie Xie!