On day 1 of learning Tableau Desktop with the Data School I learnt how to group individual pieces of geographical data and visualize this on a map (previously I had only been able to use all, one or none of the locations provided in the dataset!).
Starting with the simple visualization below showing individual states of the US...
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My first step was to choose the states I wanted to group together on the worksheet, selecting the paperclip option highlighted and then clicking 'All Dimensions'...
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Which then creates a new group to the data pane - this can then be edited by right-clicking the group then selecting 'Edit Group'...
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Here you can rename the group created as well as the field itself. More groups can be also be created in this window, for example I can add Kansas to a separate group like so...
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After adding Minnesota, Iowa and Missouri to my new group ('Group 2'), I can then apply this to my visualization and see these two groups separately from the rest of the country. I have also removed the details showing each individual state to instead focus on the entire country by clicking the minus button on my 'Country/Region' mark.
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It's that easy!