I'm working with the last version of QGIS (3.8.3-Zanzibar), and I'm trying to represent a Rule-Based Symbology from a CSV file with the following rules:

Figure 1

And the data from the prcptot column is this:

Figure 2

As you can see, all the prcptot values are negative (smaller than 0), but the output that QGIS is giving to me is the next:

Figure 3

All the red triangles should be inverted blue triangles... I think that QGIS is taking all the values as positive numbers, but I don't know why or what to do.


1 Answer 1


The rules seem not to be correct. The first rule of your example is:

"prcptot" = "prcptot" > 0 AND "p.prcptot" <=0.09

while I guess it should read:

"prcptot" > 0 AND "p.prcptot" <=0.09

Stating "prcptot" = "prcptot"is a tautology, i.e. it gets always evaluated as true. The fact that it is chained with a > 0 before the AND operator might confuse the parser, and that could be the reason why not all triangles are red.

So the full rule set would be:

"prcptot" > 0 AND "p.prcptot" <=0.09
"prcptot" > 0 AND "p.prcptot" > 0.09
"prcptot" < 0 AND "p.prcptot" <= 0.09
"prcptot" < 0 AND "p.prcptot" > 0.09
"prcptot" = 0 OR "p.prcptot" IS NULL
  • 1
    I think the last one should be IS NULL
    – MrXsquared
    Commented Oct 1, 2019 at 17:40
  • 1
    Thank you both! It worked perfectly! Commented Oct 1, 2019 at 17:42
  • @MrXsquared thanks: edited Commented Oct 1, 2019 at 17:43
  • 3
    @DobriDobrev feel free to accept this answer if it solved your question
    – MrXsquared
    Commented Oct 1, 2019 at 17:46

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