Wondering if there is a code or tool that will allow me to format the ranges and labels for classes for Natural Breaks (Jenks) classification in ArcGIS?

I understand that if I alter the ranges it defaults to "manual" classification, however I'm just interested in getting the class ranges rounded to the nearest whole numbers so that its easier to read on the map. In the images below, I like to round-off the ranges and labels 1,000-3,500, 3,500-7,000, 7,000-12,000, 12,000-25,000, etc. So this will be a "pseudo-Jenks" classification, but the goal is to make the numbers easy to read but still get the trends of a natural breaks classification. Is this possible?

Symbology tab in ArcMap

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1 Answer 1


In QGIS one can manually change the values of the ranges even if the classification chosen was an established one (Jenks, for instance). I do it very often: I first get the picture of what a set classification looks like, and then I manually adjust it so it is easy to understand.

Double-clicking in the value, a window pops up where one can introduce the limits of the class. It is very useful that the next class' lower limit automatically changes to start with the previous higher limit.

It is also very useful that the leyend automatically changes when the values are changed.

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Another alternative could be changing only the text of the leyend, and that can be done (again, in QGIS, not sure about ArcGis) in the leyend properties, double-clicking in each value.

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  • Thanks, I'll test to see if it works in QGIS. But I don' Commented Oct 24, 2016 at 16:59

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