The Problem

Following a question in Tableau Forum, I provided a solution.

The problem can be stated as follows:

Given a number of devices operating during a day, the requirement is to count the number of devices per amount of total time in operation. The question is like, how many devices operated below 10 minutes a day? how many 10-20 minutes? etc.

Wondering if there are solutions to similar problems, I googled and found that it's a fairly common problem as stated in:
http://www.theinformationlab.co.uk/2013/06/24/histograms-on-aggregate-measures/
http://community.tableau.com/thread/139950

where solutions are also provided. They are all using table calculations.

I have to admit that table calculation is one of the most dreaded functions in Tableau. Otherwise the most.

The Solution

Luckily I figured out a solution without table calc and I will present the steps here to build the histograms. I will use the same superstore data as in the Information Lab blog where we will count the number of unique customers per number of orders.

1.Drag Sum(Number of Records) to Rows shelf and turn it into discrete.
2.Drag [Customer Name] to Details shelf, a dimension needed to count the number of orders per customer.
3.Right-click and drag [Customer Name] to Columns shelf. Select CNTD().

Here is what we got:


We are almost done with the histograms, aren't we?

OK, we need to clean up a bit so that we have solid color bars and labels.

Clean up

The bars are built with many tiny bricks, each representing a customer. We need to remove those border lines between the bricks. The removal is simple:

- Click Color shelf and change the border option to None.

We got solid color bars!

To add labels, we will use reference lines on the horizontal axis.

- Select Per Cell option, Value type label, and no Line.

The histogram graph is as beautiful as it can be.


Binning the Aggregate: Sum(Number of Records)

We have yet to group Sum(Number of Records) into bins. This can be done through a calculated field [Number of Records Bins]:

Drag this new field to replace Sum(Number of Records) in rows shelf and we get:


To be a little cleaner, I removed all the row and column dividers through formatting. The workbook can be found here.