Tag: Week 33

Can you recreate this marginal histogram?

Donna ColesLeave a comment

For this week’s challenge, Lorna visualised the output of a crazy golf game she had with the latest Data School cohort, and thought it would be a fun challenge to share.

While the data set is very small, there’s several core calculations required, which we’ll start off creating.

Defining the core calculations

After connecting to the data, I initially dragged the Hole field from Measures to Dimensions (dragged it to be above the line on the data pane).

We need to know the average score per person (across all 11 holes)

Overall Average Score

{FIXED [Person]: AVG([Score])}

format this to 1dp

We also need the average score per hole

Avg Score Per Hole

{FIXED [Hole]: AVG([Score])}

format this to 1 dp

We need each person’s score up to 9 holes

Score up to 9

{FIXED [Person]:SUM( IF [Hole]<=9 THEN [Score] END)}

We need the tie break score for the 10th & 11th holes

Tie Break

{FIXED [Person]:SUM( IF [Hole]>9 THEN [Score] ELSE 0 END)}

We need the average score across 9 holes

Avg Score

[Score up to 9]/9

format to 1 dp

We need to the lowest score per person

Lowest

{FIXED [Person]: MIN([Score])}

With this information, we can then define a field we can use for sorting which is a numeric field that is a combination of multiple fields as stated in the requirements

Sort

(SUM([Score up to 9])*10000) +
(SUM([Tie Break]) * 1000) +
(SUM([Avg Score]) * 100)+
SUM([Lowest])

Building the Heat Map

On a new sheet add Score up to 9 to Rows and change it to be discrete. Repeat the same for Tie Break, Avg Score and Lowest. Then add Person to Rows and Hole to Columns.

Double click into Columns and manually type MIN(1.0) to create a ‘fake axis’. Change the mark type to bar and increase the Size to the maximum. Edit the axis to be fixed from 0 to 1 and the hide the axis. Manually increase the width of each row and set the chart to fit width.

Add Score to Colour and choose a diverging colour palette and then manually change the start & end colours to match the solution (or define your own colour style). I used #62a14b (green) and #13316d (dark blue). Check the box to use full colour range

Update the Tooltip as required.

We then need to include some indicators on the heat map. To determine the arrow indicator we first need

Previous Score

LOOKUP(SUM([Score]),-1)

and then create

Change Indicator

IF SUM([Score]) > [Previous Score] THEN ‘↗’
ELSEIF SUM([Score]) < [Previous Score] THEN ‘↘’
ELSEIF SUM([Score]) = [Previous Score] THEN ‘→’
END

(I sourced the arrow characters from https://jrgraphix.net/r/Unicode/2190-21FF)

Add Change Indicator to the Label shelf and then adjust the table calculation so it is computing by the Hole field only

We also need

Hole in 1 indicator

IF SUM([Score]) = 1 AND MIN([Hole])<> 9 THEN ‘●’ END

and

Max Shots Indicator

IF SUM([Score]) = 10 THEN ‘🙁’ END

(I used this site https://unicode-explorer.com/emoji/ for the emoji icon)

Add these to Label too and adjust label so it is aligned bottom centre, and coloured white. You may need to adjust size of font for each label item, and increase the height of each row to get the information to display.

Finalise the formatting by

  • Set the background colour of the whole sheet to #7299aa
  • Set the font of all the column headings and label headings to Tableau Medium, 9pt, white
  • Hide the Hole label heading (right click the label and hide field labels for columns)
  • Add a white border to the bars via the Colour shelf
  • Remove all column dividers
  • Remove row dividers from the pane only, ensure the row dividers for the headers remain.
  • Remove all gridlines , zero lines, axis rulers & ticks

Name the sheet HeatMap or similar.

Building the Average Score Per Person bar chart

On a new sheet, add Person to Rows and Overall Avg Score to Columns. Add a Sort to the Person pill that references the Sort field ascending

Add Overall Avg Score to the Colour shelf, and then adjust the colour scale so it uses a diverging colour scale which is then edited to use the same colour range as before and spans the same range, which means explicitly stating the start (-1) , middle (0) and end (10) values

We want to display a * against the winner

Winner Icon

IF SUM([Overall Avg Score]) = WINDOW_MIN(SUM([Overall Avg Score])) THEN ‘★’ ELSE ” END

Add this to Rows and adjust the table calculation so it is explicitly computing by Person only.

Create

Winner Label

IF SUM([Overall Avg Score]) = WINDOW_MIN(SUM([Overall Avg Score])) THEN ‘Coach Always Wins!’ END

and add this to Label along with Overall Avg Score. Increase the width of the bars to see the text and align middle left and change the font to white. Adjust the Tooltip.

Format the sheet

  • Set the worksheet background colour
  • Hide the Person column (uncheck Show Header)
  • Hide the Overall Avg Score axis (uncheck Show Header)
  • Remove all column/row dividers, gridlines, axis lines, zero lines
  • Add a white border around the bars (via the Colour shelf)
  • Increase the Size of the bars so there is a small gap between
  • Format the * to be white font
  • Hide the Winner Icon label (right click > hide field labels for rows)
  • Make the Winner Icon column as narrow as possible

Name the Sheet Avg Per Person or similar.

Building the Average Score Per Hole bar chart

On a new sheet, add Hole to Columns and Avg Score Per Hole to Rows. Add Avg Score Per Hole to Colour and adjust the scale as we did above so it ranges from green to blue and -1 to 10.

Show mark labels, adjust the tooltip. Set the background colour of the worksheet and remove all gridlines, zero lines, row/column dividers etc. Hide the Avg Score Per Hole axis and the hole labels (uncheck show header on the Hole pill). Adjust the font of the labels to be Tableau Medium and white. Add a white border around the bars. Increase the Size to leave a small gap.

Name the sheet Avg Per Hole or similar.

Building the dashboard

Set the background of the dashboard to the same colour of the worksheets.

Using containers, add a horizontal container and add a text object (for the title), the Avg Per Hole sheet and then a blank object. Remove the container that gets added with the colour legend.

Add another Horiztonal container beneath and add the Heatmap sheet and the Avg Per Person sheet.

Remove all padding. Remove all titles from the sheets. Set all the charts to fit entire view. Manually line up everything, but you’ll find you have an issue getting your horizontal bar chart to align to the player rows due to the header in the heatmap

(Note – you may notice your labels on the heat map aren’t displaying due to the space available). You can continue to adjust on Desktop so they do appear (make the heatmap have more vertical space), or wait until you’ve published to Tableau Public and see if you get the desired result… although at the point of writing , Tableau Public is having issues with the table calcs and causing odd behaviour with the display).

To fix this, go back to the Avg Per Person sheet and double click into column and manually type “” to create a dummy header row with no text. Hide the “” label (right click > hide field labels for columns). You can then adjust the height of this header label section to help get the alignment right.

Then make any final adjustments required – add the title, and any imagery etc. My published viz is here.

Happy vizzin’!

Donna

Can you compare the latest month to the prior X months average?

Donna ColesLeave a comment

Lorna set this challenge this week to test some LoD fundamentals. My solution has a mix of LoDs and table calculations – there weren’t any ‘no table calcs’ allowed instructions, so I assumed they weren’t off limits and in my opinion, were the quickest method to achieve the line graph.

Note – For this challenge, I downloaded and installed the latest version of Tableau Desktop v2022.2.0 since Lorna was using the version of Superstore that came with it. The Region field in that dataset was set to a geographic role type. I built everything I describe below using the field fine, but when I extracted the data source at the end and ‘hid all unused fields’ before publishing, the Region field reported an error (pill went red, viz wouldn’t display). To resolve, I ended up removing the geographic role from the field and setting it just to be a string datatype. At this point I’m not sure if this an ‘unexpected feature’ in the new release…

Ok, let’s get on with the build.

Building the basic viz

I started by building out the basic bar & line chart. Add Region to Rows, Order Date as continuous month (green pill) to Columns and Sales to Rows. Change the mark type to bar, change the Size to manual and adjust.

Drag another copy of the Sales pill to Rows, so its next the other one. Click on the context menu of that 2nd pill, and select Quick Table Calculation -> Moving Average

Change the mark type of the 2nd Sales pill to line.

Now click on the context menu of the 2nd Sales pill again and Edit Table Calculation. Select the arrow next to the ‘Average, prev 2, next 0’ statement, and in the resulting dialog box, change the Previous values to 3 and uncheck the Current Value box

At this point you can verify whether the values match Lorna’s solution when set to 3 previous months.

But, we need to be able to alter the number of months the moving average is computing over. For that we need a parameter

pPriorMonths

integer parameter, default to 3, that ranges from 2 to 12 in steps of 1.

Then click on the 2nd Sales pill and hold down Shift, and drag the pill into the field pane on the left hand side. This will create a new field for you, based on the moving average table calculation. Edit the field. Rename it and amend it so it references the pPriorMonths parameter as below

Moving Avg Sales

WINDOW_AVG(SUM([Sales]), -1*[pPriorMonths], -1)

Adjust the tooltip for both the line and the bar (they do differ). Ignore the additional statement on the final bar for now.

Colour the line black and adjust size. Then make the chart dual axis and synchronise axis. Hide the right hand axis. Remove Measure Names from the Colour shelf of both marks cards.

Colouring the last bar

In order to colour the last bar in each row, we need 3 pieces of information – the value of Sales for the last month, the moving average value for the last month, and an indicator of whether one is bigger than the other. This is where the LoDs come in.

First up, lets work out the latest month in the dataset.

Latest Month

DATE(DATETRUNC(‘month’,{FIXED : MAX([Order Date])}))

finds the latest date in the whole dataset and truncates to the 1st of the month. Note, this works as there’s sales in the last month for all Regions, if there hadn’t been, the calculation would have needed to be amended to be FIXED by Region.

From this, we can get the Sales for that month for each Region

Latest Sales Per Region

{FIXED [Region] :SUM( IF DATETRUNC(‘month’, [Order Date]) = [Latest Month] THEN [Sales] END)}

To work out the value of the moving average sales in that last month, we want to sum the Sales for the relevant number of months prior to the last month, and divide by the number of months, so we have an average.

First let’s work out the month we’re going to be averaging from

Prior n Month

DATE(DATEADD(‘month’, (-1 * [pPriorMonths]),[Latest Month]))

This subtracts the relevant number of months from our Latest Month, so if the Latest Month is 01 Dec 2022 and we want to go back 3 months, we get 01 Sept 2022.

Avg Sales Last n Months

{FIXED [Region]:SUM( IF DATETRUNC(‘month’, [Order Date]) >= [Prior n Month] AND
[Order Date] < [Latest Month] THEN [Sales] END)} / [pPriorMonths]

So assuming we’re looking at prior 3 months, for each Region, if the Order Date is greater than or equal to 01 Sept 2022 and the Order Date is less than 1st Dec 2022, get me the Sales value, then Sum it all up and divide by 3.

And now we determine whether the sales is above or below the average

Latest Sales Above Avg

SUM([Latest Sales Per Region]) > SUM([Avg Sales Last n Months])

If you want to sense check the figures, and play with the previous months, then pop the data into a table as below

So now we’re happy with the core calculations, we just need a couple more to finalise the visualisation.

If we just dropped the Latest Sales Above Avg pill onto the Colour shelf of the bar chart, all the bars for every month would be coloured, since the calculation is FIXED at the Region level, and so the value is the same for all rows associated to the the Region. We don’t want that, so we need

Colour Bar

IF DATETRUNC(‘month’, MIN([Order Date])) = MIN([Latest Month]) THEN
[Latest Sales Above Avg]
END

If it’s latest month, then determine if we’re above or below. Note the MIN() is required as the Latest Sales Above Avg is an aggregated field so the other values need to be aggregated. MAX() or ATTR() would have worked just as well.

Add this field to the Colour shelf of the bar marks card and adjust accordingly.

Sorting the Tooltip for the last bar

The final bar has an additional piece of text on the tooltip indicating whether it was above or below the average. This is managed within it’s own calculated field.

Tooltip: above|below

IF DATETRUNC(‘month’ ,MIN([Order Date])) = MIN([Latest Month]) THEN
IF [Latest Sales Above Avg] THEN ‘The latest month was above the prior ‘ + STR([pPriorMonths]) + ‘ month sales average’
ELSE ‘The latest month was below the prior ‘ + STR([pPriorMonths]) + ‘ month sales average’
END
END

If it’s the latest month, then if the sales is above average, then output the string “The latest month was above the prior x month sales average” otherwise output the string “The latest month was below the prior x month sales average”.

Add this field onto the Tooltip shelf of the bar marks card, and amend the tooltip text to reference the field.

Finalise the chart by removing column banding, hiding field labels for rows, and hiding the ‘4 nulls’ indicator displayed bottom right.

Creating an Info icon

On a new sheet, double click into the space within the marks card that is beneath the Detail, Tooltip, Shape shelves, and type in any random string (”, or ‘info’ or ‘dummy’). Change the mark type to shape and select an appropriate shape. I happened to have some ? custom shapes, so used that rather than create a new one. For information on how to create custom shapes, see here. Amend the tooltip to the relevant text. When adding to the dashboard, this sheet was just ‘floated’ into the position I was afte. I removed the title and fit to entire view.

My published viz is here.

Happy vizzin’!

Donna

Can you create a moving average chart with a focus on selected subcategories?

Donna ColesLeave a comment

Following the #WOW survey where practice in table calculations was the most requested feature, Lorna continues with the theme in this challenge, where the focus is on the moving average table calculation, plus a couple of extra features thrown in.

Moving average

This is based on the values of data points before and after the ‘current’ point, as defied by the parameters which will need to be created.

pPrior

Integer parameter ranging from 1 to 6 and defaulted to 3. You need to explicitly set the Step size to 1 to ensure the step control slider appears when you add the parameter to the dashboard. This will be used to define the number of data points prior to the current to use in the calculation.

Create an identical parameter pPost to define the number of data points to use after the current one.

With these parameters, we can now create the core calculation

Moving Avg

WINDOW_AVG(SUM([Sales]), (-1*[pPrior])+1, [pPost])

As the requirement states that the ‘prior’ parameter needs to include the ‘current’ value, then we need to adjust the calculation – ie if the parameter is 3, we actually only want to include 2 prior data points, as the 3rd will be the current point itself. This is what the +1 is doing in the 2nd argument of the function.

Lorna has stated that 3 Sub-Categories are grouped to form a Misc category, so we need to create a group off of Sub-Category (right click Sub-Category -> Create -> Group).

Multi-select the 4 options that need to be grouped (hold down Ctrl as you select), and then group, and rename the group Misc.

Now we can check what the calculation is doing. If you add the fields onto the view as below, and set the Moving Avg table calculation to compute using Month of Order Date only (see further below), you should be able to see that each month’s moving avg value is calculated based on the sales value of the set of previous & post months as defined by your parameters. In the image below the Moving Avg for Accessories in June 2018, is the average of the Sales values from April 2018 – Sept 2018.

With this you can start the beginnings of the viz – don’t forget to set the table calc as above.

Colouring the lines

This will be managed by using a set.

Right click on the Sub-Category (group) field -> Create -> Set. Initially select all values. Add this field to the Colour shelf. Additionally, click the Detail symbol (…) to the left of the Sub-Category (group), and select the Colour symbol, so this field is also added to the Colour shelf.

The resulting colour legend will look something like this
Edit the colour legend, then choose Hue Circle and select Assign Palette to randomly assign colours to all the options

To show the set values, click on the context menu of the Sub-Category (Group) field on the Colour shelf, and Show Set.

This will add the list of options for selection

Uncheck All so none are selected, which will change the colour legend to read ‘Out, xxx’. Edit the colour legend again, and control-click to multi select all options, then set to a single grey

Now if you select a few options, the ones selected will be coloured, while the others remain grey

Additionally add the set field onto the Size shelf and make the In option bigger than the Out.

Shading the background

For this we need to create an unstacked area chart with one measure representing the maximum moving average value for the month, and the other representing the minimum moving average value for the month. We’ll need new calculated fields for this:

Window Max Avg

WINDOW_MAX([Moving Avg])

Window Min Avg

WINDOW_MIN([Moving Avg])

If you’ve still got your data sheet available, then move Sub-Category (Group) onto Rows, then add the two newly created fields.

In this case there are ‘nested’ table calcs. You need to ensure the setting related to the Moving Avg is computing by Month Order Date only, but the setting related to the Window Max Avg (or Window Min Avg) is computing by Sub-Category (Group).

If set properly, you should see that for each month the max / min values are displayed against every row.

Back to your chart viz sheet, and add Window Max Avg to Rows. Set the table calc settings as described above, then remove the Sub-Category (group) Set field from the Colour shelf of this measure, and change the Sub-Category (group) to be on the Detail rather than Colour shelf.

Change the mark type to Area, set the Opacity of the colour to 100% and set stack Marks to be Off (Analysis Menu -> Stack Marks -> Off).

Now drag Window Min Avg onto the Window Max Avg axis and drop it when the ‘2 columns’ image appears.

This will change the view so Measure Values is now on the Rows shelf and Window Min Avg is now displayed in the Measure Values section on the left hand side.

Adjust the table calc setting of Window Min Avg to be similar to how we set the Max field. And now drag the fields so Window Min Avg is listed before Window Max Avg. Measure Names will now be on the Colour shelf of this marks card, so adjust so Window Min Avg is white and Window Max Avg is pale grey.

Now make the chart dual axes, synchronise the axes, and set the Measure Values axis to the ‘back’.

Everything else is now just formatting and adding onto a dashboard. My published viz is here.

Happy vizzin’! Stay Safe!

Donna