Here’s something with no practical use whatsoever. Today, after I finished writing the first draft of the chapter on M of my upcoming Power Query book, I got thinking about how Power View and Power Map get all the attention because of all the eye-catching demos you can create with them. And then I thought – why bother spending time finding real data for these demos when you can generate artificial data in Power Query to create patterns? So I got to work…
As you probably know, you can create animated charts in Power Map so long as you have date-based data. I therefore created a function in Power Query to draw a circle as a series of points on a graph where each point is associated with a date; I also added data for height and colour for each point. Here’s the function definition:
let
//declare function to draw a circle
CircleFunction = (CircleRadius as number, StartDate as date, Reverse as logical) =>
let
//set the radius
radius = CircleRadius,
//create a list of numbers from 0 to 359
anglelist = List.Numbers(0, 359, 1),
//function to convert degrees to radians
radians = (a) => (a * 2 * Number.PI)/360,
//create a list of 360 dates starting from the start date
unordereddatelist = List.Dates(StartDate, 360,#duration(1,0,0,0)),
//reverse the list of dates if the Reverse parameter is True
datelist = if Reverse then List.Reverse(unordereddatelist) else unordereddatelist,
//generate the list of points on the graph, one for each angle and date
positionlist = List.Transform(anglelist, each
{_, datelist{_}, Number.Cos(radians(_)) * radius,
Number.Sin(radians(_)) * radius, Date.Month(datelist{_}),
Number.Abs(Number.Cos(radians(_)))*10}),
//convert the list of points to a table
outputtable = Table.FromRows(positionlist, {"Angle", "Date", "x", "y", "Colour", "Size"}),
//set data types
ChangedType = Table.TransformColumnTypes(outputtable,
{{"Angle", type number}, {"Date", type date}, {"x", type number},
{"y", type number}, {"Colour", type number}, {"Size", type number}})
in
ChangedType
in
CircleFunction
I then created another Power Query query to call this function 30 times to create 30 circles with different radiuses:
let
//generate a list of numbers from 0 to 29
circlelist = {0..29},
//generate a list of 30 dates starting on 1 January 2014
datelist = List.Dates(#date(2014,1,1), 30,#duration(1,0,0,0)),
//call the Circle() function 30 times
tablelist = List.Transform(circlelist, each Circle(_+5, datelist{_}, Number.Mod(_,2)=0)),
//combine the resulting tables into a single table
positionlist = Table.Combine(tablelist)
in
positionlist
And here’s the result of the query plotted on a map using Power Map:
Pretty, isn’t it? You can download the workbook with the Power Query query and the Power Map tour here.
