Function Repository Resource:

ToWellKnownText

Source Notebook

Convert graphics primitives to well-known text (WKT)

Contributed by: Anton Antonov

ResourceFunction["ToWellKnownText"][arg]

Converts graphics primitives in arg into Well-known text strings.

Details

ResourceFunction["ToWellKnownText"] converts graphics primities Point, Line, Polygon into Well-Known Text (WKT) strings.

Point[{x_,y_, ___}] is converted into a string that starts with "POINT".

Point[{p1,p2,p3,..}] is converted into a string that starts with "MULTIPOINT".

Line[{p1, p2, …}] is converted to a string that starts with "LINE".

Line[{{p₁₁, p₁₂, …}, {p₂₁, p₂₂, …}, …}] is converted to a string that starts with "MULTILINESTRING".

Polygon[{p1,p2,…}] is converted to a string that starts with "POLYGON".

Polygon[{{p₁₁, p₁₂, …}, {p₂₁, p₂₂, …}, …}] is converted to a string that starts with "MULTIPOLYGON".

Lists of graphics primitives are converted to WKT strings that start with "GEOMETRYCOLLECTION".

Examples

Basic Examples (2)

Here a graphics specification of three points is converted into a WKT string:

In[1]:=

Out[1]=

Here a multi-element graphics specification is converted into a WKT string:

In[2]:=

Out[2]=

Scope (7)

Over a single point:

In[3]:=

Out[3]=

Over multiple points:

In[4]:=

Out[4]=

Over a line:

In[5]:=

Out[5]=

Over multiple lines:

In[6]:=

Out[6]=

Over a polygon:

In[7]:=

Out[7]=

Over multiple polygons:

In[8]:=

Out[8]=

Over a collection of polygons and lines:

In[9]:=

Out[9]=

Properties and Relations (2)

Here is multi-element graphics:

In[10]:=

Out[10]=

Here is the corresponding WKT string:

In[11]:=

Out[11]=

Multi-polygon specification:

In[12]:=

Graphics[{FaceForm[Opacity[0.5]], Polygon[{{{0, 0}, {0, 1}, {1, 1}, {1, 0}}, 2*{{0.1, 0.1}, {0.1, 1}, {1, 1}, {1, 0.1}}}]}, Frame -> True]

Out[12]=

Here is the corresponding WKT string:

In[13]:=

Out[13]=

Possible Issues (2)

ToWellKnownText does not check the dimensions of the given graphics specs.

Well-known Text (WKT) specifications allow for representation of polygons with holes. For example:

POLYGON ((35 10, 45 45, 15 40, 10 20, 35 10), (20 30, 35 35, 30 20, 20 30))

The function ToWellKnownText does not make WKT strings for polygons-with-holes.

Publisher

Related Links

Version History

1.0.0 – 12 September 2022

Related Resources

Author Notes

Well-known Text (WKT) is used a lot in Geo-computations. A closely related format is Well-known Binary (WKB). WKT and WKB are often converted to GeoJSON.

License Information

This work is licensed under a Creative Commons Attribution 4.0 International License