5

I have a layer of the world that contains 200 rows.

I am required to color the map with six selected colors, the rainbow colors.

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I figure that I can save selected countries and save them separately.

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Once they saved I can upload them and make the color ramp I needed.

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However, I was wondered is there a faster way to do this without making six layers and without choosing each country manually in the Layer Styling bar panel.

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6

Following further clarification by Nitzan Matan, this is another map representation.

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This categorization was made by round((y(centroid($geometry))+80)/30) .

To divide latitude range (-90 ~ +80) in this sample data from Natural Earth into 6 zones (bands), I first added 80 and divided by 30. You will need to modify these numbers according to your dataset.

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Now change the color to fit with your rainbow palette.

NB One caveat - you will notice Alaska is green. If you want it to be like Russia and Canada, consider breaking US into parts.

  • Very smart!, Can you explained more about the latitude range? – Nitzan Matan Dec 9 '18 at 9:36
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    @NitzanMatan Yes, more specifically the latitude ranges (-90.00000 ~ 83.64513) and found as part of Extent in the Layer Properties | Information. But I need to know only the y-coord of centroid so it does not have to be such precise. – Kazuhito Dec 9 '18 at 9:48
3

As you are using QGIS 3.4.2, you can use Topological coloring Tool, which is in the Processing Toolbox | Cartography.

Start this tool and give 6 (any number of colors you want to have) in the Minimum number of colors and hit Run. It will return a new layer Colored with an additional integer field color_id.

So the last step is to open the Layer Property of this layer and set Categorized color scheme on the color_id column (field). You then change each of these 6 random colors to your rainbow palette.

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  • The new color id are random, I need then to be from the bottom up like the flag. – Nitzan Matan Dec 9 '18 at 8:41
  • Sorry @NitzanMatan I honestly do not understand your comment. Could you expound it a little bit more? – Kazuhito Dec 9 '18 at 8:58
  • Sure, in your answer you made 6 colored id, They are scattered randomly. In group 1 there are row both in Africa and the U.S. I need that Russia and Canada will be one color, U.S and Europe and so on. Thanks! – Nitzan Matan Dec 9 '18 at 9:10
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    Aah, color bands like the flag? Gotcha! Thanks @NitzanMatan for clarification. – Kazuhito Dec 9 '18 at 9:15

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