Hi all,
I'm pretty sure I got fairly close with this, but now I'm too deep into the problem and can't see the wood for the trees.
The dataset is Covid-19, and I'm looking, for example, at the number of cases per country.
I would like to have a line for each country, with the line starting at a common point, such as when a country reaches 500 cases.
I have manually created it and adjusted the dates on the Tab 'Over 500 cases'.
But I would like to be able to adjust the number, and for new countries to automatically work.
I had thought I would be able to use a level of detail to find the minimum date when a value was first reached,
calculate the difference between that date and the latest date in the data.
I ran into issues as (maybe) the USA numbers (and some others) are made up of multiple states, whereas another country would just be a single line.
You'll see some attempts to do it on the following fields:
- Over Case Limit
- Over X Cases
- Min Country
- Different in Dates
- Baselined Dates
Workbook on Tableau Public here:
eg:
Hi Jean,
You can use one of table calculation help function index() to achieve the common baseline comparison. An example will be on Tableau blog Top 10 Tableau table calculations | Tableau Software case 2.
Back to your case, here is the solution.
Step 1. Create one calculated field [# of days Since 500 cases] whose formula is simple as INDEX().
Step 2. Drag and Drop [Date] into details and choose date value day as details, also change the mark type to Line chart.
Step 3. Replace [Manually Adjusted Date] on columns with [# of days Since 500 cases], configure Table Calculation direction as Computing Using > Date.
you can find the solution in attachment.
Cheers
Jimmy Zhang
