I have a polygon shapefile and a (merged) line shapefile (both are zipped). When I use Vector -> Analysis Tools -> Sum Line Lengths on these shapefiles, I get a layer with some of the LENGTHS filled with numeric values. However, a significant portion of the LENGTHS are now 'nan', even when the COUNT is a non-zero value.

Here are a few possible explanations, but I'm not sure which one is correct:

  1. Error with the shapefiles.
  2. Shapefiles are too big.
  3. The data type of the LENGTH field is inappropriate.
  4. I need to unzip them.

I've tried doing the same with a few of the unmerged line shapefiles and this problem still seems to occur.

  • Quick thought - have you checked for any null geometry in your files (and then eliminate any such features)? – MappaGnosis Oct 20 '18 at 9:35

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.