Helping you see and understand your data
If you have heard of Tableau, you might be familiar with their mission, which is to ‘help people see and understand data’. Just like Ronseal Quick Drying Wood-stain, Tableau ‘does exactly what it says on the tin’. If you’re not already a firm fan of Tableau Desktop, do yourself a favour and check it out! The team at Perception have long been convinced of the power of Tableau and we are passionate about spreading the word.
To say there have been a few minor announcements from Tableau in recent times would be an understatement. The last few weeks have seen the arrival of Tableau 2018.1, new offerings and the much awaited Tableau Prep, the topic of this blog post. Tableau’s Chief Product Officer Francois Ajenstat, Tableau Prep Product Manager Maraki Ketema and Senior Manager Ashley Bass delivered a webinar summarising the highlights, which you can tune into here.
I’ve been spending time getting familiar with Tableau Prep since I attended a virtual training course and I can immediately see the value it offers to those working with data. If you haven’t had an opportunity to have a look yet, you can download a trial here. Getting started is very easy and there are plenty of training videos available. I’m going to outline a few ‘quick wins’ below to get you started.
Tableau Prep – Giving your data the once over
When I’m first presented with a data-set, I want to get a feel for what I’m dealing with. Checking how many rows and columns is a good place to start. With Tableau Desktop, you can drag the measure Number of records to a view and see how many rows are present. Tableau Desktop doesn’t allow you to instantly see how many columns your data-set contains, and as someone who has spent years using Excel, this used to irk me slightly as you can do it in Excel with one click. Tableau Prep tells you how many columns you have as soon as you connect to your data, which makes me happy, and needless to say it offers a whole lot more in terms of letting you ‘see and understand’ your data. I absolutely love the overview it provides and it’s almost effortless.
In the example below, I’m connecting to data from the International Organisation for Migration, which has been made available for the latest project on the Viz for Social Good site. When you open Tableau Prep there is a similar look and feel to that of Tableau Desktop, with a navy Connections pane on the left. Clicking on the ‘+’ button allows you to navigate to your data.
One key difference between Tableau Prep and Tableau Desktop is that you don’t get a preview of rows in your data-set right after connecting to the data. Once you have connected to a source table, an input step will be created in the white area known as the flow pane (see below). The input pane is underneath the flow pane and allows you to determine certain criteria on the left and gives you an overview of all your columns on the right. You see how many fields there are, the respective data types and some sample values. This initial view is valuable as it’s easy to scan down the screen and get a feel for the fields present. You can filter, modify field attributes and choose which fields to bring forward in the data preparation process. There is also a search box so you can quickly identify if a particular field is present.
Input step and pane
You need to add a step in order to display a view of the rows of data, aka the data grid. This so-called clean step is invaluable in terms of shining a light on your data, even if you’re not actually going to do anything else in terms of modification. To do so you simply click on the ‘+’ symbol (see above beside the input step) and choose the first option.
Clean step, profile pane and data grid
Once you have created a clean step, you will see the profile pane, which is the middle panel above, directly under the flow pane. You will also see the data grid which displays the actual records at the bottom of the screen. It’s fair to say that in general, the Tableau Desktop (part of the newly branded Tableau Creator) ‘drag and drop’ approach makes it very easy to visualise and get an understanding of your data. The beauty of this profile pane in Tableau Prep is that you don’t even have to do that in order to get a comprehensive visual representation of your data. This window really provides a huge amount of information in a very consumable, visual manner.
Note that in the top left-hand corner of the profile pane you can see the number of columns and the rows that are being considered. Hovering over the number of Rows gives you the exact number rather than the rounded version. It’s important to establish whether you’re looking at your entire data-set or simply a sample or sub-set which has been taken from your source. You will see a notification here if you have a sample rather than the entire data-set. Sampling is done behind the scenes and means that you’re not seeing the profile of your entire data, rather a subset. You can make some choices as regards the sampling criteria in the Input pane discussed above.
The profile pane allows you scan across and assess the contents of each field, or search for a field in the top right-hand corner. You see underlying trends and distributions for your whole data-set and you can interact to highlight more insights. From here you can also make necessary changes to cleanse your data. All changes are recorded and shown to the left of the profile pane (when you expand using the arrow in the grey panel) in a way that’s easy to track.
Just do it!
We are obviously just touching the surface here in terms of going through the functionality, but I hope I’ve shown that with just a few clicks and only a small investment of time, you can get a lot of value. To take things to the next stage you will need to learn more about what’s on offer in terms of cleansing and shaping your data to get the real benefit. If you are comfortable working with Tableau, then a lot of concepts will be familiar. It will just be a matter of understanding how to implement in Tableau Prep and learn some new techniques. You can pivot and aggregate your data, group, create calculated fields and combine data from disparate sources with unions and joins. The key benefit is that you can create complex flows containing several stages, which allows you to prepare your data in such a way that you can answer even more challenging business questions. The visual presentation allows you to track everything easily, providing transparency and the ability to view the impacts of the changes on the underlying data. You can also preview your results and do preliminary analysis in Tableau Desktop by right clicking on any step in a flow. Actually getting started with a new tool can sometimes be half the battle, so I’d recommend you download and connect to your favorite data-set and take it from there! As is the case with Tableau Desktop, the Online Help and training videos serve as a valuable resource. If you have started using Tableau Prep and would like an opportunity to practice, the latest challenge on the Workout Wednesday site will give you just that.
Thanks for reading!
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