Feature request #4857: Add unit type to $area calculation - QGIS Application - QGIS Issue Tracking

Feature request #4857

Add unit type to $area calculation

Added by Pierre-Luc Auclair almost 13 years ago. Updated over 8 years ago.

Status:	Closed
Priority:	Normal
Assignee:	-
Category:	-
Pull Request or Patch supplied:	No	Resolution:
Easy fix?:	No	Copied to github as #:	14690

Description

When I calculate areas, it would be useful to specify directly the unit type I want in my field.

The way I see it working is this : $area(unit)

Where "unit" is a unit abbreviation, say km, m, ha, etc.

I always find transferring square meters to other units with calculations cumbersome as I have a hard time remembering how much I should divide or multiply values.

Thanks !

Associated revisions

Revision 9f772bce
Added by Nyall Dawson over 8 years ago

Add API call for setting preferred distance unit for QgsExpression

(refs #13209, #12939, #4857)

Revision ddbdcf8a
Added by Nyall Dawson over 8 years ago

Fix project unit confusion (pt 2): add project distance unit setting

Adds a new option in project properties to set the units used for
distance measurements. This setting defaults to the units set in
QGIS options, but can then be overridden for specific projects.

The setting is respected for length and perimeter calculations in:
- Attribute table field update bar
- Field calculator calculations
- Identify tool derived length and perimeter values
- Default unit shown in measure dialog

Also adds unit tests to ensure that length and perimeter calculated
by attribute table update bar, field calculator and identify tool
are consistent wrt ellipsoidal calculations and distance units.

(refs #13209, #12939, #2402, #4857, #4252)

Revision dfdcec89
Added by Nyall Dawson over 8 years ago

Fix project unit confusion (pt 3): add area unit settings with a
ton of available area units (eg m2, km2, mi2, ft2, yd2, ha, ac,
etc)

Adds a new option in both the QGIS setting and project properties to
set the units used for area measurements. Just like the distance
setting, this defaults to the units set in QGIS options, but can
then be overridden for specific projects.

The setting is respected for area calculations in:
- Attribute table field update bar
- Field calculator calculations
- Identify tool derived length and perimeter values

Also adds unit tests to ensure that area calculated by attribute table
update bar, field calculator and identify tool are consistent wrt
ellipsoidal calculations and area units.

TODO: make measure tool respect area setting

(refs #13209, #4252 and fixes #12939, #2402, #4857)