Tourism in Spain: Analyzing National Tourist Flows Using Interactive Visualizations

1. Introduction

Visualizations are graphical representations of data that allow for the simple and effective communication of information linked to them. The possibilities for visualization are very broad, from basic representations such as line graphs, bar charts or relevant metrics, to visualizations configured on interactive dashboards.

In this section "Visualizations step by step" we are periodically presenting practical exercises using open data available on datos.gob.es or other similar catalogs. In them, the necessary steps to obtain the data, perform the transformations and relevant analyses to, finally obtain conclusions as a summary of said information, are addressed and described in a simple way.

Each practical exercise uses documented code developments and free-to-use tools. All generated material is available for reuse in the GitHub repository of datos.gob.es.

In this specific exercise, we will explore tourist flows at a national level, creating visualizations of tourists moving between autonomous communities (CCAA) and provinces.

 

Access the data laboratory repository on Github.

Execute the data pre-processing code on Google Colab.

In this video, the author explains what you will find on both Github and Google Colab.

2. Context

Analyzing national tourist flows allows us to observe certain well-known movements, such as, for example, that the province of Alicante is a very popular summer tourism destination. In addition, this analysis is interesting for observing trends in the economic impact that tourism may have, year after year, in certain CCAA or provinces. The article on experiences for the management of visitor flows in tourist destinations illustrates the impact of data in the sector.

3. Objective

The main objective of the exercise is to create interactive visualizations in Python that allow visualizing complex information in a comprehensive and attractive way. This objective will be met using an open dataset that contains information on national tourist flows, posing several questions about the data and answering them graphically. We will be able to answer questions such as those posed below:

• In which CCAA is there more tourism from the same CA?
• Which CA is the one that leaves its own CA the most?
• What differences are there between tourist flows throughout the year?
• Which Valencian province receives the most tourists?

The understanding of the proposed tools will provide the reader with the ability to modify the code contained in the notebook that accompanies this exercise to continue exploring the data on their own and detect more interesting behaviors from the dataset used.

In order to create interactive visualizations and answer questions about tourist flows, a data cleaning and reformatting process will be necessary, which is described in the notebook that accompanies this exercise.

4. Resources

Dataset

The open dataset used contains information on tourist flows in Spain at the CCAA and provincial level, also indicating the total values at the national level. The dataset has been published by the National Institute of Statistics, through various types of files. For this exercise we only use the .csv file separated by ";". The data dates from July 2019 to March 2024 (at the time of writing this exercise) and is updated monthly.

Number of tourists by CCAA and destination province disaggregated by PROVINCE of origin

The dataset is also available for download in this Github repository.

Analytical tools

The Python programming language has been used for data cleaning and visualization creation. The code created for this exercise is made available to the reader through a Google Colab notebook.

The Python libraries we will use to carry out the exercise are:

• pandas: is a library used for data analysis and manipulation.
• holoviews: is a library that allows creating interactive visualizations, combining the functionalities of other libraries such as Bokeh and Matplotlib.

5. Exercise development

To interactively visualize data on tourist flows, we will create two types of diagrams: chord diagrams and Sankey diagrams.

Chord diagrams are a type of diagram composed of nodes and edges, see Figure 1. The nodes are located in a circle and the edges symbolize the relationships between the nodes of the circle. These diagrams are usually used to show types of flows, for example, migratory or monetary flows. The different volume of the edges is visualized in a comprehensible way and reflects the importance of a flow or a node. Due to its circular shape, the chord diagram is a good option to visualize the relationships between all the nodes in our analysis (many-to-many type relationship).

Figure 1. Chord Diagram (Global Migration). Source.

Sankey diagrams, like chord diagrams, are a type of diagram composed of nodes and edges, see Figure 2. The nodes are represented at the margins of the visualization, with the edges between the margins. Due to this linear grouping of nodes, Sankey diagrams are better than chord diagrams for analyses in which we want to visualize the relationship between:

•  several nodes and other nodes (many-to-many, or many-to-few, or vice versa)
• several nodes and a single node (many-to-one, or vice versa)

 

Figure 2. Sankey Diagram (UK Internal Migration). Source.

 

The exercise is divided into 5 parts, with part 0 ("initial configuration") only setting up the programming environment. Below, we describe the five parts and the steps carried out.

5.1. Load data

This section can be found in point 1 of the notebook.

In this part, we load the dataset to process it in the notebook. We check the format of the loaded data and create a pandas.DataFrame that we will use for data processing in the following steps.

5.2. Initial data exploration

This section can be found in point 2 of the notebook.

In this part, we perform an exploratory data analysis to understand the format of the dataset we have loaded and to have a clearer idea of the information it contains. Through this initial exploration, we can define the cleaning steps we need to carry out to create interactive visualizations.

If you want to learn more about how to approach this task, you have at your disposal this introductory guide to exploratory data analysis.

5.3. Data format analysis

This section can be found in point 3 of the notebook.

In this part, we summarize the observations we have been able to make during the initial data exploration. We recapitulate the most important observations here:

We can observe in columns one to four that the origins of tourist flows are disaggregated by province, while for destinations, provinces are aggregated by CCAA. We will take advantage of the mapping of CCAA and their provinces that we can extract from the fourth and fifth columns to aggregate the origin provinces by CCAA.

We can also see that the information contained in the first column is sometimes superfluous, so we will combine it with the second column. In addition, we have found that the fifth and sixth columns do not add value to our analysis, so we will remove them. We will rename some columns to have a more comprehensible pandas.DataFrame.

5.4. Data cleaning

This section can be found in point 4 of the notebook.

In this part, we carry out the necessary steps to better format our data. For this, we take advantage of several functionalities that pandas offers us, for example, to rename the columns. We also define a reusable function that we need to concatenate the values of the first and second columns with the aim of not having a column that exclusively indicates "National Total" in all rows of the pandas.DataFrame. In addition, we will extract from the destination columns a mapping of CCAA to provinces that we will apply to the origin columns.

We want to obtain a more compressed version of the dataset with greater transparency of the column names and that does not contain information that we are not going to process. The final result of the data cleaning process is the following:

5.5. Create visualizations

This section can be found in point 5 of the notebook

In this part, we create our interactive visualizations using the Holoviews library. In order to draw chord or Sankey graphs that visualize the flow of people between CCAA and CCAA and/or provinces, we have to structure the information of our data in such a way that we have nodes and edges. In our case, the nodes are the names of CCAA or province and the edges, that is, the relationship between the nodes, are the number of tourists. In the notebook we define a function to obtain the nodes and edges that we can reuse for the different diagrams we want to make, changing the time period according to the season of the year we are interested in analyzing.

We will first create a chord diagram using exclusively data on tourist flows from March 2024. In the notebook, this chord diagram is dynamic. We encourage you to try its interactivity.

Figure 5. Chord diagram showing the flow of tourists in March 2024 aggregated by autonomous communities.

The chord diagram visualizes the flow of tourists between all CCAA. Each CA has a color and the movements made by tourists from this CA are symbolized with the same color. We can observe that tourists from Andalucía and Catalonia travel a lot within their own CCAA. On the other hand, tourists from Madrid leave their own CA a lot.

Figure 6. Chord diagram showing the flow of tourists entering and leaving Andalucía in March 2024 aggregated by autonomous communities.

 

We create another chord diagram using the function we have created and visualize tourist flows in August 2023.

Figure 7. Chord diagram showing the flow of tourists in August 2023 aggregated by autonomous communities.

We can observe that, broadly speaking, tourist movements do not change, only that the movements we have already observed for March 2024 intensify.

Figure 8. Chord diagram showing the flow of tourists entering and leaving the Valencian Community in August 2023 aggregated by autonomous communities.

The reader can create the same diagram for other time periods, for example, for the summer of 2020, in order to visualize the impact of the pandemic on summer tourism, reusing the function we have created.

For the Sankey diagrams, we will focus on the Valencian Community, as it is a popular holiday destination. We filter the edges we created for the previous chord diagram so that they only contain flows that end in the Valencian Community. The same procedure could be applied to study any other CA or could be inverted to analyze where Valencians go on vacation. We visualize the Sankey diagram which, like the chord diagrams, is interactive within the notebook. The visual aspect would be like this:

Figure 9. Sankey diagram showing the flow of tourists in August 2023 destined for the Valencian Community.

 

As we could already intuit from the chord diagram above, see Figure 8, the largest group of tourists arriving in the Valencian Community comes from Madrid. We also see that there is a high number of tourists visiting the Valencian Community from neighboring CCAA such as Murcia, Andalucía, and Catalonia.

To verify that these trends occur in the three provinces of the Valencian Community, we are going to create a Sankey diagram that shows on the left margin all the CCAA and on the right margin the three provinces of the Valencian Community.

To create this Sankey diagram at the provincial level, we have to filter our initial pandas.DataFrame to extract the relevant information from it. The steps in the notebook can be adapted to perform this analysis at the provincial level for any other CA. Although we are not reusing the function we used previously, we can also change the analysis period.

The Sankey diagram that visualizes the tourist flows that arrived in August 2023 to the three Valencian provinces would look like this:

Figure 10. Sankey diagram August 2023 showing the flow of tourists destined for provinces of the Valencian Community.

We can observe that, as we already assumed, the largest number of tourists arriving in the Valencian Community in August comes from the Community of Madrid. However, we can verify that this is not true for the province of Castellón, where in August 2023 the majority of tourists were Valencians who traveled within their own CA.

6. Conclusions of the exercise

Thanks to the visualization techniques used in this exercise, we have been able to observe the tourist flows that move within the national territory, focusing on making comparisons between different times of the year and trying to identify patterns. In both the chord diagrams and the Sankey diagrams that we have created, we have been able to observe the influx of Madrilenian tourists on the Valencian coasts in summer. We have also been able to identify the autonomous communities where tourists leave their own autonomous community the least, such as Catalonia and Andalucía.

7. Do you want to do the exercise?

We invite the reader to execute the code contained in the Google Colab notebook that accompanies this exercise to continue with the analysis of tourist flows. We leave here some ideas of possible questions and how they could be answered:

• The impact of the pandemic: we have already mentioned it briefly above, but an interesting question would be to measure the impact that the coronavirus pandemic has had on tourism. We can compare the data from previous years with 2020 and also analyze the following years to detect stabilization trends. Given that the function we have created allows easily changing the time period under analysis, we suggest you do this analysis on your own.
• Time intervals: it is also possible to modify the function we have been using in such a way that it not only allows selecting a specific time period, but also allows time intervals.
• Provincial level analysis: likewise, an advanced reader with Pandas can challenge themselves to create a Sankey diagram that visualizes which provinces the inhabitants of a certain region travel to, for example, Ourense. In order not to have too many destination provinces that could make the Sankey diagram illegible, only the 10 most visited could be visualized. To obtain the data to create this visualization, the reader would have to play with the filters they apply to the dataset and with the groupby method of pandas, being inspired by the already executed code.

We hope that this practical exercise has provided you with sufficient knowledge to develop your own visualizations. If you have any data science topic that you would like us to cover soon, do not hesitate to propose your interest through our contact channels.

In addition, remember that you have more exercises available in the section "Data science exercises".