Geography.ToWellKnownText

The Geography.ToWellKnownText M function is a powerful tool in Power Query that allows users to transform geographical data into a Well-Known Text (WKT) format. WKT is a text markup language that represents spatial objects in a human-readable format.

In this article, we will explore the M code behind the Geography.ToWellKnownText function and how it can be used to transform geographical data.

What is the Geography.ToWellKnownText function?

The Geography.ToWellKnownText function is a built-in function in Power Query that converts a geographical object to a Well-Known Text (WKT) string. The function takes a single argument, which is a geography value.

The geography value can be a point, line, or polygon. The function then converts the geography value to a WKT string, which can be used in various geographic information systems (GIS) applications.

How does the Geography.ToWellKnownText function work?

The Geography.ToWellKnownText function works by converting a geography value to a WKT string. The function uses the Open Geospatial Consortium (OGC) standard for WKT representation.

The WKT format represents a geography value as a string of text. The string is made up of different elements that represent the geometry of the spatial object. The elements include the type of geometry, the coordinates of the spatial object, and any other necessary information.

The Geography.ToWellKnownText function works by parsing the geography value and generating a string of text that conforms to the WKT standard.

Examples of using the Geography.ToWellKnownText function

Let’s take a look at some examples of using the Geography.ToWellKnownText function in Power Query.

Example 1: Converting a point to WKT

Suppose we have a table with a column named “Location,” which contains the latitude and longitude of different points.

To convert the points to WKT, we can use the following M code:

let

Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText(“i45WMjQwNLE0NjJQ0lFKSVEyNVHiDc5MqeozCjJSMjAyNjK3Ss7MygAVQA”, BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Location = _t]),

#”Changed Type” = Table.TransformColumnTypes(Source,{{“Location”, type geography}}),

#”Added Custom” = Table.AddColumn(#”Changed Type”, “WKT”, each Geography.ToWellKnownText([Location]))

in

#”Added Custom”

let

Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText(“i45WMjQwNLE0NjJQ0lFKSVEyNVHiDc5MqeozCjJSMjAyNjK3Ss7MygAVQA”, BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Boundary = _t]),

#”Changed Type” = Table.TransformColumnTypes(Source,{{“Boundary”, type geography}}),

#”Added Custom” = Table.AddColumn(#”Changed Type”, “WKT”, each Geography.ToWellKnownText([Boundary]))

in

#”Added Custom”