I have a file with data fields which I have imported as CSV. When I look at the Field Attribute Table, the empty fields appear clearly as NULL values. However when I interpolate the data, the NULL values are being tenter image description herereated as 0 (zero).

How do I get around that?

  • Which interpolation tool are you using?
    – ndawson
    May 9 '18 at 20:48
  • I have used IDW interploation May 10 '18 at 12:42

You could try to filter your data (in layer properties > source > Query Builder with the expression : "MY_FIELD" is not NULL) to remove the null value before interpolating

  • Thank you. That really worked for me. But I find it counter intuitive. I expected the interpolation routine to honor the null values as NULL. I am new to QGIS. May 10 '18 at 13:11

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