QGIS » QGIS Desktop

When using fTools Random Points to generate a specified number of points per polygon using an input field, it crashes if I direct it to assign 0 points to any polygon.

I have to reformat my data to create at least one dot per polygon and then manually remove the extra points later if they are supposed to accurately show 0.

For example, if I want to run a dot density map that has one dot per 25 people, and one of the polygons is a lake that has 0 people in it, I still have to assign 1 dot to it or else it will crash. This would be inaccurate, so I have to manually remove it later.

Appears to be a common issue, see http://gis.stackexchange.com/questions/16830/dot-density-maps-in-qgis

Error text below:

An error has occured while executing Python code:

Traceback (most recent call last):
File "/Users/kentonngo/.qgis/python/plugins/fTools/tools/doRandPoints.py", line 121, in accept
self.randomize(inLayer, outPath, minimum, design, value)
File "/Users/kentonngo/.qgis/python/plugins/fTools/tools/doRandPoints.py", line 211, in randomize
else: points = self.loopThruPolygons(inLayer, value, design)
File "/Users/kentonngo/.qgis/python/plugins/fTools/tools/doRandPoints.py", line 258, in loopThruPolygons
sPoints.extend(self.simpleRandom(value, sGeom, sExt.xMinimum(), sExt.xMaximum(), sExt.yMinimum(), sExt.yMaximum()))
File "/Users/kentonngo/.qgis/python/plugins/fTools/tools/doRandPoints.py", line 166, in simpleRandom
add = ( 70.00 - 40.00 ) / n
ZeroDivisionError: float division

Python version:
2.6.1 (r261:67515, Jun 24 2010, 21:47:49)
[GCC 4.2.1 (Apple Inc. build 5646)]

QGIS version:
1.9.90-Alpha Alpha, e13e45f

Python path: ['/Users/kentonngo/.qgis/python/plugins/sextante', '/Applications/QGIS-1.9.app/Contents/MacOS/../Resources/python', '/Users/kentonngo/.qgis/python', '/Users/kentonngo/.qgis/python/plugins', '/Applications/QGIS-1.9.app/Contents/MacOS/../Resources/python/plugins', '/Library/Frameworks/SQLite3.framework/Versions/3/Python/2.6', '/Library/Frameworks/GDAL.framework/Versions/1.9/Python/2.6/site-packages', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python26.zip', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/lib-dynload', '/Library/Python/2.6/site-packages', '/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/PyObjC', '/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/wx-2.8-mac-unicode', '/Users/kentonngo/.qgis/python/plugins/fTools/tools', '/Users/kentonngo/.qgis/python/plugins/mmqgis/forms', '/Users/kentonngo/Desktop']