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I am trying to apply a color ramp to a shape using percentage values where red would be low and green would be high. The data ranges from 74% to 100%, but I need the minimum value to be 0%, so that 74% would actually display as light green. It currently shows as red because it is the lowest value in the class.

I have other indicators to plot on the same map and want to use the same color ramp, where the lowest value will be much lower than 74%, and I need the color ramp to be consistent across maps. Such that red is always in the 0 end of the values.

I know I can manually change the values in the classes, but I am hoping there's a more automated way to do this.

I'm using QGIS 3.4.1

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  • Is this possible in ArcMap? I don't see a + sign in my symbology.
    – Edwin
    Mar 7, 2019 at 16:57
  • If you have a new question, please ask it by clicking the Ask Question button. Include a link to this question if it helps provide context. - From Review
    – Vince
    Mar 7, 2019 at 17:22

1 Answer 1

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There is a possibility to manually add a new category (it work as well in Categorized or Graduated symbology) by clicking on the '+' sign right to the 'classify' button, so you just have to add a 0 class to shift your color ramp from 74-100 to 0-100

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setting a 5 classes equal interval classification then clicking the "+" then choose a red to green color ramp give you 6 classes, 0 being red, then 74-79 orange and the last green, if you want a true graduation you have to set more classes (in the exemple below I get to a total of 20 classes to simulate classe of around 5%)

You have to choose/attribute the color ramp after adding the 0 classes

enter image description here

enter image description here

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  • I tried that, but it doesn't shift the color map. I end up with two red classes.
    – Justin DeNormandie
    Jan 9, 2019 at 13:18
  • You have to choose/attribute the color ramp after adding the 0 class. just attribute the same color ramp and it should work
    – J.R
    Jan 9, 2019 at 13:48
  • Just tried that. Now 0 - 74% is just one red class, and then the next class is 74-79% at orange. If I apply equal intervals, then it just removes the 0 class again.
    – Justin DeNormandie
    Jan 9, 2019 at 13:59
  • setting a 5 classes equal interval classification then clicking the "+" then choose a red to green color ramp work for me. give more detail if that's not working for you
    – J.R
    Jan 9, 2019 at 14:09
  • This is what I'm doing: * Select Graduated Symbols * Select Column Indicator (contains 162 values between 74% - 100%) * Class set to 5 * Click + sign (now its 6 classes) * Select color ramp Now the color ramp is distributed as follows: * Red: 0 - 0 * Orange: 0.74 - 0.79 * Yellow: 0.792 - 0.844 * etc
    – Justin DeNormandie
    Jan 9, 2019 at 14:18

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