2024 Week 19 | Power BI: Radial Plots using Line and Scatter Charts with trig functions

1. Obtain 5 years of data from https://geodesyapps.ga.gov.au/sunrise or use your own alternatives

For the Scatter Plot:

1. Model the Data in Power Query to create a table consisting of Year-Month, Year Number, Month Number, Hours
2. Create a measure to determine the angle of the points for each month. TIP: degrees = 360/number of categories ; to convert from degrees to radians, multiply the number of degrees by π/180
3. Create a measure to determine the distance of the points from the centre. TIP: For 5 years, plot the first year as radius = 1, and the last year as radius = 6. Calculate the difference of the current year and last year.
4. Create a measure to calculate the X and Y coordinates. TIP: x = rSinθ ; y = rCosθ ; where r = radius and θ = angle
5. create an image of equally spaced concentric circles (using PowerPoint layer circles of width and height 1, 2, 3, 4, 5 etc. and save as SVG)
6. Add a Scatterplot to the visual canvas
7. Add this image and the plot area background and adjust the transparency to suit
8. Add the Year-month field to the Values field well, and the X and Y measures to the relative field wells and the hours field to the Size field well
9. Format the visual

For the radial lollipop:

1. Model the Data in Power Query to create a table consisting of Year-Month, Year Number, Month Number, Hours (per step 1 above)
2. In PQ or Using a DAX Calculated Table, create a summarized table of the average of daily hours by year and month and add a column “Point”, with data values of “Point”. Union this summarized table with another create a summarized table with values of zero for each year and month and add a column “Point”, with data values of “Base”. The Base points will be the start of the lollipop, the Point points will be the end of the lollipop
3. Create a calculated column for Angle (per scatter plot above)
4. Calculated column for X and Y (per scatter plot above)
5. Add the X, Y fields to a line chart visual
6. Place the month as the category field
7. Add markers, format the visual as desired using custom labels to show the Average Daylight hours for Points = “Points” and null for Points = “Base” instead of the Y values.