idea Set symbology’s lower value manually in ArcGIS PRO in ArcGIS Pro Ideas

Set Minimum Break Value Below Data's Minimum Statistic In Classified Raster Symbology

RyanCoodey — Mon, 20 Sep 2021 17:32:30 GMT

In Classified Renderers, when manually setting the "Break Values", you can set a break greater than the maximum statistic, but you can NOT set a break lower than the minimum. It forces you to the value of the minimum statistic. What if you have data that might go lower than this in the future? What if you just want to set nice clean breaks? I don't see why the smallest break must be greater than or equal to the minimum statistic.

This can be gotten around by loading values from another data set, but this is a lot of extra work to setup that data as needed.

Minimum value when classifying manually

PhilippMarty — Wed, 17 Aug 2011 12:36:09 GMT

In ArcMap: If you want to set break values manually during a classification, the minimum break value is not allowed to be smaller then the datas minimum value. Of course there is a work around (--> import a predefined lyr-file), but it would be helpful to define the minimum break value without the mentioned limitation.

Re: Set Minimum Break Value Below Data's Minimum Statistic In Classified Raster Symbology

CordulaGöke — Fri, 21 Aug 2020 10:51:53 GMT

The same applies to classified symbology for vector data. At the moment it is in ArcGIS Pro even possible to set the upper value of the first class lower than the range that ArcGIS automatically calculates. The lower value does not get changed in this process. Connected to this is the option to recalculate the range with higher sample size. This option should be moved from advanced to the histogram menue. If you have already chosen manually changed classes, the lower value will not update, so you have to change back to one of the automatic class options and manually enter the ranges afterwards. Also for importing symbology from .lyr does not offer the option to adapt the lower value to the class range in the current data.

Set symbology’s lower value manually in ArcGIS PRO

CordulaGöke — Fri, 21 Aug 2020 13:25:03 GMT

Lower class value of the lowest class cannot be manually changed (it was the same in ArcGIS).

You can update by choosing advanced-> sample size-> set sample size up, if you have not chosen “manual interval”. If you have chosen “manual interval”, not even that will work. If you realize too late that not all your data is covered or want to import symbology, there is no way around to set all class values manually again. There is no option only to update the lower value. The new sampling will always change the class values based on the chosen method and the new histogram.

You can actually set the upper value of the first class lower than the automatically estimated lower value. This is different from ArcGIS and changes the situation from being annoying to being a bug.

The new thing is that you can add “out of range” as a new feature in pro, but again the same, there is no way to update the range once you are in manual interval, you can change the upper value for the lowest interval, but the data will be shown as out of range and that is wrong and a bug.

The preferred solution is to be able to set the lower value manually, than you do not need to update with large samples and you can prepare the symbology for possible future lower values in dynamic data. Additionally, it would be easier to move the sampling from the advanced to the histogram-menu.

In the example I imported symbology from another layers based on latitude onto the column longitude. It is completely out of range, but normally I would want to keep the class limits. I calculated the statistics for the lon column in the table and then chose an upper value which definitely lies in the range of Lon. I added out of range symbols, otherwise the map would be simply white. The points would not be selectable. Choosing to update the range during support would change all class limits when anautomatic classification was chosen in the original layer and not update when "maual interval" is chosen.

Re: Set symbology’s lower value manually in ArcGIS PRO

CordulaGöke — Tue, 25 Aug 2020 08:39:40 GMT

Today I learnedthat it is possible to text edit the *.lyrx. So if I take the step to export to lyrx, it is actually possible.

Re: Set Minimum Break Value Below Data's Minimum Statistic In Classified Raster Symbology

ChelseaRozek — Thu, 15 Jul 2021 15:51:49 GMT

First time running into this issue for me. Surprised to see this idea from 2010. More than 10 years later, Pro can't do this. I'm trying to make a COVID-19 vaccination rate map with graduated colors. They want a set of colors each 10% from 0-100% so we can compare maps over time. I can't set an interval range for lower than our lowest vaccination rate.

Re: Set symbology’s lower value manually in ArcGIS PRO

lzk222 — Tue, 16 Aug 2022 19:28:08 GMT

Yet another instance where ESRI comes up short. QGIS handles this much better. My advice is to create a new category column based on the ranges of the values you wish to symbolize and then symbolize based Unique values. For instance, I want to create 5 classes and one "No Data" class. I write the logic (CASE WHEN is a good option) for the classes and just produce the text outputs in a new column (ddi_cat). This is QGIS

Note I created the new column in QGIS but there is probably a way to do it in ArcPro. In general, I highly recommend getting familiar with QGIS, especially when it comes to symbology. It has superior UI, functionality and customizability. I generally map things out in QGIS and then transfer them over to ArcPro for the web mapping features.

Re: Set symbology’s lower value manually in ArcGIS PRO

CraigWilliams — Tue, 16 Aug 2022 19:57:10 GMT

The lower value is shown and editable in the histogram view as shown in this GIF.

The example @lzk222 shows can also be done with an arcade expression for class breaks or unique value symbology. In that case the expression itself is configuring classes.

Re: Set symbology’s lower value manually in ArcGIS PRO - Status changed to: Already Offered

CraigWilliams — Tue, 16 Aug 2022 19:57:20 GMT

Re: Set symbology’s lower value manually in ArcGIS PRO

DWR_BuckEhler — Wed, 24 Aug 2022 21:05:19 GMT

@CraigWilliams , I think you missed the point. Users would like to sort by using a 'Lower value' in the graduated symbology classes rather than an upper value.

I just ran into this today and have an example for acres. I would like symbols to go something like this:

≥50

≥ 400

≥ 2000

≥ 4000

≥ 8000

≥ 12000

≥ 20000

≥ 30000

Below is the best that I can do currently:

We could do a lot of modifications to the labels to clean this up but it takes a lot of time and if anything changes, we have to start over again.

Thanks,

Buck

Re: Set symbology’s lower value manually in ArcGIS PRO

MaxMolello — Thu, 06 Oct 2022 14:40:11 GMT

Craigs answer works for me, changing the minimum value in the histogram forces the classes lower than the data minimum values, although I would have never known that was editable, it doesn't look like it is until you double click the number.

On a side note, the classes make it seem like everything below your current class is included since it says the upper value of each class is less than or equal to the value, I think that is misleading if that is actually limited to the set lower value in the histogram.

Re: Set symbology’s lower value manually in ArcGIS PRO

CordulaGöke — Wed, 22 Feb 2023 11:03:17 GMT

I agree with @MaxMolello , @CraigWilliams answer actually works, but it is not obvious, that the values in the histogram are editable . Great, problem solved, I would just wish ArcGIS Pro was more intuitive. As histogram, I would expect some connection to the data distribution, in reality, it shows simply the class size graphically.

Re: Set symbology’s lower value manually in ArcGIS PRO

StevenTouzel — Fri, 21 Apr 2023 20:15:20 GMT

I was able to adjust the Min and Max values of the Raster Stretch Symbology by using the Minimum Maximum Stretch type:

Re: Set symbology’s lower value manually in ArcGIS PRO

Jonathan_Schroeder — Thu, 18 Jan 2024 15:47:52 GMT

I just wanted to second @MaxMolello's response: Yes, the histogram allows adjusting the minimum value (and I'm glad to know that now!), but it doesn't initially appear to be adjustable there (a problem), and labeling the lowest class range only as "≤ [upper limit]" is inaccurate and misleading (a bug, in my opinion).

I realize now that a map I published where I thought I was showing all valid data was actually omitting some symbols for small values because I'd assumed that "≤ [upper limit]" was exactly what it said it was.

Re: Set symbology’s lower value manually in ArcGIS PRO

dns — Tue, 23 Jan 2024 01:04:39 GMT

There are not enough cues that tell the user that the lower value is editable. I think that could be a major source of the confusion.

Re: Set symbology’s lower value manually in ArcGIS PRO

DougBrowning — Tue, 11 Feb 2025 23:19:25 GMT

I am stuck trying to do this script. If the range is really small like =.0003 to .00003 it will completely ignore my custom breaks and use a totally made up scale. If the range is medium the breaks take but then the map gets all one color - the min value color. This is totally wrong and users get the wrong idea. In my case I have -100 to 100 for percent's. If the range is -7 to 8 then I get ALL of the map getting the color of -40. These maps are generated in a GP tool on the fly and need them all to have the same symbology.

Totally stuck. Any ideas.

sym = rasterLayer.symbology sym.updateColorizer('RasterClassifyColorizer') # was Condition Number sym.colorizer.colorRamp = project.listColorRamps('Prediction')[0] sym.colorizer.classificationField = "Value" sym.colorizer.breakCount = 10 #sym.colorizer.noDataColor = {'RGB': [255, 255, 255, 100]} # manual breaks # this will fail on small time periods if len(sym.colorizer.classBreaks) == 10: sym.colorizer.classBreaks[0].upperBound = -100 sym.colorizer.classBreaks[0].label = "Over -40%" sym.colorizer.classBreaks[1].upperBound = -40 sym.colorizer.classBreaks[1].label = "-30% to -40%" sym.colorizer.classBreaks[2].upperBound = -30 sym.colorizer.classBreaks[2].label = "-20% to -30%" sym.colorizer.classBreaks[3].upperBound = -20 sym.colorizer.classBreaks[3].label = "-10% to -20%" sym.colorizer.classBreaks[4].upperBound = -10 sym.colorizer.classBreaks[4].label = "0% to -10%" sym.colorizer.classBreaks[5].upperBound = 10 sym.colorizer.classBreaks[5].label = "0% to 10%" sym.colorizer.classBreaks[6].upperBound = 20 sym.colorizer.classBreaks[6].label = "10% to 20%" sym.colorizer.classBreaks[7].upperBound = 30 sym.colorizer.classBreaks[7].label = "20% to 30%" sym.colorizer.classBreaks[8].upperBound = 40 sym.colorizer.classBreaks[8].label = "30% to 40%" sym.colorizer.classBreaks[9].upperBound = 100 sym.colorizer.classBreaks[9].label = "Over 40%" else: arcpy.AddMessage("Warning Trend Rasters may not work with short time frames. Trying reduced symbols.") sym.updateColorizer('RasterStretchColorizer') sym.colorizer.colorRamp = project.listColorRamps('Condition Number')[0] sym.colorizer.stretchType = "StandardDeviation" rasterLayer.name = "Total Change" rasterLayer.symbology = sym

If I save out the map I got the correct range but colors are wrong.

Why is it getting blue?

Also really wish we could set an exact range. This upper bound thing is so confusing esp with negative numbers. Plus what I want to leave certain values out? Let me set a upper and lower and call it a day please.

Then if I add a interval in Pro it still lumps -7 to -100 at the top. This seems way wrong right?

thanks