I have a layer with the field size. I did some mistake with the value and now I need the values multiplied by 16.

But instead of going through 500 lines and recalculating them I would like QGIS to do that.

So I tried to mark all features and then I hit the field calculator. Now I selected to take the values and chosen the size column. In the expression I had $Id * 16.

But the result was that I got: 0 16 36

instead of e.g.: 47 38 67

So how can I take a whole column with simple operations?

1 Answer 1


What about "size" * 16 in the field calculator expression?

  • 1
    Ohh c'mon, so easy =) Where could I have found a tutorial for this very easy stuff. Found really nothing in terms of that. =/
    – kwoxer
    Feb 4, 2015 at 16:16
  • 1
    I won't follow the discussion here unless you mark the answer as accepted :D. Honestly, I do not know where to find a guide for that. Here you have a list of functions to use hub.qgis.org/wiki/17/List_of_Field_Calculator_Functions Feb 4, 2015 at 16:24
  • 1
    :O I was not aware of that. An extra suggestion: Make a copy of your vector data layer and start playing with and exploring functions in the field calculator, if you go to Function list->Fields and Values and double click on any attribute name, it will put it in the expression with the correct syntax. That's a way of learning. Feb 4, 2015 at 16:37
  • I don't think I will need more than a simple recalculating, so it's fine with the basics. And it works as it should with the field calculator. So thanks.
    – kwoxer
    Feb 4, 2015 at 17:24

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