After years of using Tableau, I was finally given a use case that would allow me to create an Arc Chart; I always strive to build the best visualization for the client’s requirements. The client wanted to visualize the number of issues that were being escalated from each level. In this tutorial, I will go through the steps to create an Arc Chart.

**Data**

Our data set will consist of:

Step | Start Point | End Point | Path | Escalations |

A to B | 1 | 2 | 1 | 10 |

A to B | 1 | 2 | 181 | 10 |

A to C | 1 | 3 | 1 | 4 |

A to C | 1 | 3 | 181 | 4 |

A to D | 1 | 4 | 1 | 2 |

A to D | 1 | 4 | 181 | 2 |

A to E | 1 | 5 | 1 | 1 |

A to E | 1 | 5 | 181 | 1 |

B to C | 2 | 3 | 1 | 5 |

B to C | 2 | 3 | 181 | 5 |

B to D | 2 | 4 | 1 | 2 |

B to D | 2 | 4 | 181 | 2 |

B to E | 2 | 5 | 1 | 1 |

B to E | 2 | 5 | 181 | 1 |

C to D | 3 | 4 | 1 | 4 |

C to D | 3 | 4 | 181 | 4 |

C to E | 3 | 5 | 1 | 2 |

C to E | 3 | 5 | 181 | 2 |

D to E | 4 | 5 | 1 | 4 |

D to E | 4 | 5 | 181 | 4 |

Copy and paste this into Tableau and look at the data.

*Note: We could have used the left and right functions to isolate the level and then use Calculated Fields to work out the Start Point and End Point, but for simplicity we I will include this in the data set. But if you want to try, use something like IF LEFT([Step],1) = “A” THEN 1…*

**Calculated Fields**

We will create a **Path (bin)** object by:

- Right click on
**Path** - Go to
**Create**,**Bins…** - In Edit [Path] set the
**Size of bins**to 1 - Click
**Ok**

Create the following Calculated Fields by as follows:

**Index: **INDEX()-1

**WC_PI: **WINDOW_MAX(MAX(PI()))

**WC_End Point: **WINDOW_MAX(MAX([End Point]))

**WC_Start Point: **WINDOW_MAX(MAX([Start Point]))

**WC_Step Size: **([WC_End Point]-[WC_Start Point])/2

**WC_Escalations: **WINDOW_MAX(MAX([Escalations]))

**X: **((COS([Index]*[WC_PI]/180))*[WC_Step Size])

**Y: **SIN([Index]*[WC_PI]/180)*[WC_Step Size]

Now that we have all the Calculated fields, we will now go about building our worksheet.

## The Worksheet

Let’s start by dragging our Calculated fields onto the worksheet:

- Drag
**Step**onto**Detail Mark** - Drag
**Path (Bin)**onto the**Details Mark** - Drag
**X**onto**Columns**- Right click on
**X**, select**Compute Using**and choose**Path (Bin)**

- Right click on
- Drag
**Y**onto**Columns**- Right click on
**Y**, select**Compute Using**and choose**Path (Bin)**

- Right click on
- Change the
**Mark Type**to**Line** - Drag
**Index**onto the**Path Mark**- Right click on
**Index**, select**Compute Using**and choose**Path (Bin)**

- Right click on
- Drag
**WC_Escalations**onto the**Size Mark**- Right click on
**WC_Escalations**, select**Compute Using**and choose**Path (Bin)**

- Right click on

You should now see the following:

Ok, we are not quite there yet, but we are getting there.

- Edit the
**X**Calculated Field by changing it to:- ((COS([Index]*[WC_PI]/180))*[WC_Step Size])
**+[WC_Step Size]+[WC_Start Point]**

- ((COS([Index]*[WC_PI]/180))*[WC_Step Size])

This will shift the half circles and will give you the following:

And we are done, at least from a technical perspective.

Now do the following:

- Remove
**Gridlines**and other lines, so that we get a**white background** - Fix the x-axis to be from
**0.75**to**5.25** **Hide**the X and Y Axis- Add some
**tooltips** - Add
**Labels**underneath the visualisation in a dashboard

In the end, hopefully, you will have something that looks like this.

This type of chart can be used to highlight:

- Time spent at each stage of a manufacturing process
- Drop-offs on during an online sales process
- Visitor drop-offs for views on a website

I hope you enjoyed following this blog and, as always, let me know your comments below, or on Twitter at **@thoang1000**