Tell me more ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.
up vote 1 down vote favorite

I have a project in QGIS where one of the things I need to do is work from a police data file with 9 months of crime information, linked to details of county population (age, employment, etc) to report the % of different crimes in each county (7 counties). When I follow the example screenshot given, word for word, to work out a %, I get an message which says: "An error occured while evaluating the calculation string.".

I'm not sure where i'm going wrong. Any guidence would be a lifesaver.

share|improve this question
1  
Did you mean to attach a screenshot? – Simbamangu May 12 '12 at 17:08

1 Answer

up vote 1 down vote

The equation for the field calculator should simply be something like:

(FIELDNAME_1 / FIELDNAME_2) * 100

Where FIELDNAME_1 = the field with the number of a particular crime and FIELDNAME_2 = the field with the total number of crimes.

Remember that the data should be stored as numbers. If its as a string bad things will probably happen (possibly the reason for your error).

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

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