Week 49 of #WorkoutWednesday2019 was Luke’s last challenge of the year, so following a poll he posted a ‘notably tough’ challenge.

On the face of it, it didn’t look too bad…. I figured it would involve a trellis chart for the small multiples, set actions (for the state selection), and something table calculation related to crack the ranking. Hovering over the state label for each small multiple, I also figured some dual axis was probably at play. The bit that actually looked most tricky to me initially, was displaying the States just as their shapes.

Single State viz

I decided to build the single state viz first. I created a set (Selected State) based off the [State] field, and selected California as the state ‘in’ the set.

I then started to build the viz simply by double-clicking on State (which automatically adds State to the detail shelf, and the automatically generated Long & Lat fields to the rows & columns. I added the Selected State set to the filter shelf, which immediately restricted the data to California, and I changed the mark type to filled Map.

To isolate the display just to the State itself, I figured would be something to do with the various Map Layer options available (menu Map -> Map Layers); I wasn’t sure exactly what but found by unchecking every pre-selected option, I got a ‘clean’ display.

Changing the opacity of the mark colour to 0 and setting the border to red gave me the desired display.

Maybe the State shape wasn’t going to be as much of an issue as I thought….?

The cities needed to be displayed as circular marks, so I knew this would need a dual axis to make this work. I duplicated the Latitude field (hold ctrl as you click and drag the field) and did the following :

• changed the mark type of the duplicated field to circle
• added City to the Detail shelf
• added Sales to the Size shelf
• changed the colour of the mark to blue, upped the opacity to 50% and removed the shape border

I then made the chart dual axis and increased the size of the circles to suit.

Finally I added State and Sales to the Label shelf of the Map marks card and adjusted the Label formatting to suit.

Ranking

So the requirement was to show the top 25 states in a ‘grid’ or ‘trellis’ format ordered by the state with the most sales.

However there was a subtlety to this:

• the grid should always show 25 states
• the selected state should not display in the grid
• the overall rank of the state should display, so if the 3rd largest state is selected, the displayed ranking would be 1, 2, 4, 5, 6… up to 26; 3 would be omitted from the list.

The best way to explain how I tackled this, is to show the info in a tabular format.

Firstly, create a table of Sales by State sorting the State by Sales desc

Apply a Quick Table Calculation of Rank to the SUM(Sales) pill. Then edit the table calculation, setting the rank to be unique and fixing the Compute Using to apply over State.

Add the Selected State pill alongside State, and as California is still our selected state, you see we now have two ‘1’s. This is because we fixed the table calculation to State, so its now being applied for each ‘In/Out Selected State’

This is the table calculation we want to use to filter our data to get the ‘top 25’ fields. With ‘California’ selected as being ‘in the set’ and therefore the selected state, we need the next 25 states to the be ones showing in the grid. This being from New York to Oklahoma.

Holding down ctrl and then dragging the Sum(Sales) pill to the filter shelf (ie duplicating the pill), you can set it to show at most 25

However, the ‘rank’ displayed against each row, isn’t the rank we want to show on the viz. New York is the 2nd largest state, so should be labelled no 2, not no 1 as shown above.

We need another version of the Sales rank. Add Sales back into the chart, and again apply a Quick Table Calculation of Rank.

The 2nd rank is now showing values 1 – 26, and if you edit the table calc, you’ll see it automatically has set itself to ‘table down’ which is actually being applied to both State and the In/Out Selected State. Alter the table calc to be unique and fix it to apply to State & In/Out Selected State, which will ensure the values remain the same regardless as to how you move pills around.

This second rank is what is used to display the ‘overall rank.

Finally, we’ve still actually got 26 states shown, when we only want the 25 states ‘out’ of the set displayed. We simply apply the sneaky trick to ‘hide’ the In (click on the ‘In’, right-click and select Hide).

Change the set value to Ohio for example, and re-show the hidden data (click on In/Out Selected Set pill and Show hidden data). You’ll see Ohio is 8th in the overall rank, but is ‘in’ the set so ranked 1 in the ‘top 25’ filter rank.

When I come to build the map trellis later, it is these table calcs and techniques I will have applied.

Trellis Chart

In this instance we have a fixed number of states to display (25), to show in a 5×5 grid; 5 rows and 5 columns. Each of the 25 states we have needs to be assigned a row number and a column number.

Let’s go back to the tabular display to help with this. With the display just showing the 25 States ‘out’ of the set (by hiding the ‘In’), let’s add INDEX() to the view. INDEX() is a table calculation most often used to number rows. INDEX() is set to compute over the State only (so the numbers 1-25 are listed). Note this is giving the same information as the Sales ranking discussed above, and we could reference the same field, but INDEX() is more generic and referenced in many trellis chart solutions, so let’s stick with that.

What we’re looking to achieve, is the first 5 rows listed, to appear in the 1st row, across 5 columns. Rows 6-10 would be in the 2nd row etc etc. I need to build

Cols

FLOAT(INT((INDEX()-1)%5))

This takes the Index value and subtracts 1, and returns the remainder when divided by 5 (%5=modulus of 5). Storing the final output as a float will become clearer later.

Rows

FLOAT(INT((INDEX()-1)/5))

This takes the Index value and subtracts 1, and returns the integer part of the value when divided by 5. Storing the final output as a float will become clearer later.

Adding these on to the table, and again setting the table calculation to compute by State only, you get

and if we shuffle the pills around to create the rows & columns, and keep just the pills we need we get

But it’s all upside-down : we need California top left, not bottom left. We can fix this by editing the Rows axis, and reversing it.

Now by simply changing the mark type to Map, we can get the shape states to show – it’s like magic! You’ll need to increase the size to see them properly.

Side note – this was actually quite a revelation; it took some time for me to get to this, having unsuccessfully had views with Lat & Long displayed (as that’s what a map chart always needs right?), resulting in the state shapes being positioned all over the place. Writing this blog and reproducing steps as I type, has made things seem much simpler, than when I was tackling the challenge initially!

As you can see, things aren’t perfect yet, but we’re on the right track. The axis need editing to extend them. Rows is set from -0.5 to 5, and Cols from -0.5 to 4.5 (this is why we needed to set the field to be FLOATs).

The colour of the mark also needs adjusting to match what we did when building the single state viz.

The label positioning isn’t also right, even if you change the alignment, so move the State from the Text to the Detail shelf and don’t show any labels. Then create an additional axis on the rows by duplicating the Rows field to exist alongside, then ‘type’ into the second instance and change to Rows+0.5

Make this dual axis, synchronise and change mark type to Text. Make sure the opacity on the colour is increased back to 100% and adjust the size of the text.

Now it’s just a case of tidying this view to match the requirements; adding additional fields to the Text shelf, removing axis, row/column lines and gridlines etc.

Once done, both the views can be added to a dashboard, and the ‘select state’ interactivity is achieved using a Set Action dashboard action.

And that’s it. As stated I did have some struggles when building initially, but as most things, it’s down to the path you happen to follow. If I’d initially built based on the order I’ve authored this blog, and the tabular views I’ve built to demonstrate techniques, I wouldn’t have had any problem. But it’s all valuable learning experiences and adds to my understanding!

My version of the viz is published here.

Happy vizzin!

Donna