Tableau Visualization -- How to build Gnatt Chart

Gnatt chart can be useful in showing status of large number of items and things with respect to time. An example of that is displaying the various flight time from each route and determine which has the longest delay or longest flight time as reflected on the chart by the size of each Gnatt.

In my example, i am going to show for a given year, how are the order to ship time is like for each product in the warehouse.

So start with product dimension (Row section) and order date (Column section):

change the order date display format to 'exact date'

Now to figure out the exact order to ship time, we simply go a date diff between order date and ship date. This is similar to timestampdiff function in SQL, but in tableau we use a different syntax by create a new calculated field called 'Time to ship' with the following formula:

DATEDIFF('day',[Order Date],[Ship Date] )

Sometimes, there are different types of shipping. So if you want to make a distinction among the dimension with certain categorization, we simply put the categorizing field into the color window. So in this case, different product has different ship mode that we want to distinguish by, so simply drop ship mode into the color section as shown below and the chart is colored.

Now move 'time to ship' field into size windows. The size of each bar will start to differ more noticeably based on the number of days differ.

We also want to include the ship date as part of the display in details for validation purpose. So we pick ship date and drop it into detail windows

Now the chart is done. We can move the mouse over any bars and the detail information will display from the details:

here you can see the time to ship for applicance is 17 days and it shows you the date ordered and the date shipped

Thanks

Until next time