0

I'm working with agriculture area data in MapInfo. I downloaded the boundary file from StatCan (call it STC), and a freehand draw tool downloaded here https://tinyurl.com/ydarsnq8 (call it DRW)

I can draw an area (DRW) over the StatCan boundary file (STC). In some cases DRW falls over 2 or 3 regions (polygon) in the STC (call it STC1, STC2, STC3...etc)

How can I calculate the proportion DRW over each STC regions (i.e. DRW/STC1, DRW/STC2..etc)

Reason, each STC has a unique 'production' value and I need to compute the 'production' value for my DRW.

2

I have created two TAB files in Mapinfo - Poly1 and Poly2. Each TAB file has an attribute "Area". Poly2 has an attribute "poly1_area".

To calculate the proportion of Poly1 in the Poly2 table, Go to the Table Menu, then click on Update Column...

Table to Update: Poly2

Column to Update: poly1_area

Get Value from Table: Poly1

Calculate: Proportion Sum

of: Area

enter image description here

Click the Join button and specify where object from table Poly1 intersects object from table Poly2. You can choose whatever you need here.

enter image description here

Map: Poly1 (black), Poly2 (red):

enter image description here

Poly1 browser:

enter image description here

Poly2 browser:

enter image description here

Calculating the proportion is a matter of dividing poly1_area by Area.

  • thanks for the feedback! quick Q: what version are you using? currently using 8.5 and looking to upgrade. – coolintake Jan 16 '18 at 15:47
  • That was version 15. – Fezter Jan 16 '18 at 18:38
  • in the first step of your solution (apologies, total newbie), how do I create .TAB files? When I upload the shapefile I can view the Table for the boundary file, but when I use the draw tool to draw the polygon on top, not sure how to view/create a Table for that shape...riding the struggle bus here – coolintake Jan 17 '18 at 15:59
  • Please ask this as another question. Comments aren’t meant for extended chat and further questions – Fezter Jan 17 '18 at 18:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.