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- March 6, 2020 at 11:21 pm #87234Spectator@oluwole
Data visualization is a vital part of data analysis that involves taking data or information and representing it in a visual context, such as a graph or a map. It is the communication of relationships inherent in data with images. Data visualization is important because it makes it easier to spot trends, outliers, and patterns in big and small data. Therefore, useful data visualizations should represent complicated datasets in more explicit and more concise ways.
Creating visualizations is not as straightforward as one might suppose, especially if the data set involved is enormous. To this effect, data visualization tools such as Tableau, FineReport, D3, Infogram, Datawrapper, Power BI, and even Microsoft Excel can be used to make the designer’s job easier.
The preference of a data visualization tool is for a designer, based on several factors such as ease of use, variety of visualizations, and cost considerations. As such, it is hard to single out a “best” tool. However, some standout tools are capable of creating a wide variety of visualizations and are significantly more straightforward to use than other options in the market. One of such tools is Tableau Public.
This post introduces the Tableau Public visualization software. We will also see how to get it installed, set it up, and finally, create our first map project.
Tableau is a business intelligence tool for data visualization. It boasts a variety of options, such as a desktop app, hosted and server online versions, and a free public option (Tableau Public). Tableau allows users to create and distribute interactive and shareable dashboards, depicting patterns, trends, and densities of data in charts and graphs. Tableau allows for connection to files, relation data sources, and big data sources to fetch and process data.
Data Visualization is one of the most useful professional skills to develop. The better you can convey your points visually, the better you can leverage that information. – Tableau
Tableau Public is the public version of Tableau, which is free to use for anyone desirous of a powerful way to create data visualizations that can be used in different settings. It boasts an extensive gallery of infographics and displays that have been created by various users. These visualizations serve as an inspiration to users who are interested in creating theirs.
In this post, we will be making use of Tableau Public as it is mainly similar to the paid version. The most significant difference between both versions is that Tableau Public does not allow you to save your workbooks to local storage while Tableau provides that option.
Let’s get started on its installation!
Installing Tableau Public
To install the software, visit the Tableau Public homepage. Enter your email address and click on “Download the App”. The download link is then captured, and the .exe file for windows should begin downloading (about 360MB).
After the download, open the downloaded file. Accept the terms and conditions and click on the “Install” button. After installation, the Start Screen of Tableau is shown.
Creating your Workbook
The first step to create a Tableau Notebook is to connect it to a file. Tableau provides options to connect to different file formats such as Excel, Text files, JSON, PDFs, and more. For our example, our dataset is a CSV file titled “Jobs.csv” which can be downloaded here. It shows the job openings available and details about these vacancies.
CSV files are Text files, so on the “Connect” dashboard, we select “Text File”.
Upon the selection, your File Explorer pops up for the selection of the file you want to connect to, in this case, “Jobs.csv”. Navigate accordingly to the location where the file was downloaded and click on “Open”.
This action takes you to the “Data Source” sheet, where you can preview the data you just loaded. You can also see the total number of rows in the dataset on the right. At the bottom left, you can click on Sheet 1 and rename it as “Map” to begin working on creating your visualization.
The worksheet primarily consists of a Data pane to the Left, a Show Me option to the Right, and the Chart area in the center. The Data pane is consists of two panels – Dimensions and Measures. Dimensions are the data fields that cannot be measured or aggregated while Measures, as its name implies, can be measured, aggregated, or used to perform mathematical operations.
The “Show Me” option to the right of the window is used to select the chart option you desire. It makes suggestions based on the number of data fields being selected. The Chart area is where the visualizations are seen and modified. Data from the “Data” pane can be dragged to the Chart area and formatted to make the desired graph or figure.
Formatting the Data Fields
To create a map visualization, there is a need to have a Longitude and Latitude attribute in the data set. We can see from our dataset that such attributes are non-existent. All we have is a “Location” attribute, and we’d have to work with that. Tableau can generate the coordinates of locations in the data set. Let’s see how!
First, we need to create two additional fields titled “City” and “State” from the Location attribute. To do this, click on “Jobs” in the Data Pane. This takes you to your “Data Source” page;
Next, click on the dropdown in the “Location” column header and select split.
This creates two new columns – one representing the City, the other representing the State. Rename these columns by clicking on the drop-down and selecting Rename.
Return to Sheet 1, and you will observe that the newly created features have been added to the “Dimensions” pane. To generate their coordinates, we need to format both attributes as their respective geographical roles.
For the “City” entry, right-click “City” and under the Geographical Role, select City. Ditto for the “State” entry, select “State/Province”. This generates the Latitude and Longitude attributes within the dataset, and these can be seen in the Measures panel.
Creating the Map
First, we drag the “Latitude” and “Longitude” entries to the “Rows” and “Columns” fields, respectively, in the chart area.
Next, to view the number of jobs based on States and City;
- Drag the “Number of Values” entry in the “Measures” pane to the “Size” option in the “Marks” field.
- Drag the “State” and “City” to the “Details” option in the “Marks” field.
If the map is yet to be displayed, it might be due to the presence of “Unknown” fields in your data set. Such an instance is seen in the above image. Tableau uses your country to reference the City and State data entries. This error is therefore expected if you are anywhere besides the United States. To correct this, click on the “Unknown” field. In the pop-up dialog, select “Edit Locations”. Edit the “Country/Region” field and select “USA” under the “Fixed” category. Click “Okay” to close the dialog. Now, our map should be up!
Each ring represents the cities where the job openings are. Their sizes indicate the number of available jobs in that city. Hovering over each data point reveals the details about that entry. For instance, in the city of Minneapolis, in the state of Minnesota (MN), there are six job records.
Saving your project
Next, we save the project using “Ctrl + S”, and a Sign In dialog pops up. You are required to sign in or create a new account for free. After this, you see the option to edit the title of the workbook and save it to your Tableau Public account.
Usually, your profile opens in your web browser, showing the just successfully published workbook.
Tableau Public is a free tool for analysts and other professionals seeking an easy and convenient way to represent their data in a myriad of ways visually. In this post, we saw how to install the software and successfully created a Map project!
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