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Symbology / Legend Order for No Value Features

sgambrel_Bouldercounty

Hello,

I have a web map that shows the FEMA-regulated Floodplain in my community. In the FEMA data, there is a Zone Subtype field that is used to classify features in the commonly-used categories of Floodway / 100-Year Floodplain / 500-Year Floodplain. This field has values for Floodway and 100-year Floodplain, but no value for 100-Year Floodplain.

I can symbolize each of these categories distinctly, however because the 100-Year Floodplain is "No Value", it doesn't seem that I can re-order it in the legend to show up where it logically should, between Floodway and 500-Year Floodplain.

I also do not appear to be able to suppress the "Area of Minimal Flood Hazard" - basically everything NOT regualted floodplain - from showing up on the legend. This does not need to be on the legend.

Is there any way to remedy this? The current layer list / legend looks ridiculous as-is. See the screenshot below for an illustration.

Two notes: The source of this data is a REST mapservice; I am using the "0" layer. I don't think there's any flexibility in this. Also, both FEMA and ESRI host this data which is somehow correctly symbolized, but I cannot use that as we have modified the FEMA data slightly, as we consider all floodplain above a certain elevation to be floodway.

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Laura

You should be able to drag the Area of Minimal Flood Hazard down to the other area and uncheck it - will disappear from legend. Also your symbols style is set to 3 colors (classes) change it to include 4 and your other one should be in that main list.

sgambrel_Bouldercounty

That doesn't work and is precisely the issue. "No Value" is in this case a legitamite value, for the 100-year floodplain. The Map Viewer insists on putting No Value ar the bottom. You can see that it is not moveable because it doesn't have the dotted handle at the left. Likewise, the Area of Minimal Risk cannot be dragged below No Value, and dragging it "into" it groups it with the 100-Year Floodplain.

Laura

Can you post a link to the FEMA data here?

The 6 dots left to Area of Minimal Risk should allow you to drag it below. Did you try changing the symbol style as stated above to see if that resolved any issues?

sgambrel_Bouldercounty

https://maps.bouldercounty.org/arcgis/rest/services/HAZARD/FLOODPLAIN_FEMA_REGULATED/MapServer/0

The Zone Subtype Field is the one that is used for the 3 commonly used zones.

Laura

Sorry but that says restricted access. You may need to send the link from the direct source.

sgambrel_Bouldercounty

I woried that might happen... Here's a Feature Layer made from that REST endpoint:

https://arcg.is/rWyf8

Laura

Ah ok I see. I can't edit but have you tried populating those fields that are listed as no value with 100 yr?

sgambrel_Bouldercounty

Unfortuantely Nope. The commonly-used floodplain classifications don't exactly align with the FLD_ZONE Field. Both zones A & AE can be either Floodway or 100-year Floodplain, depending on the Zone Subtype (either 1100 or no value). Zone X is either 500-Year Floodplain or Area of Minimal Risk, depending on the Zone Subtype (either 500 or 2000).

Unfortunately I and everyone else using FEMA data need to use "No Value" to symbolize the 100-Year Floodplain.

Laura

We also use this for local gov. If you look at their viewer it appears they are using AE / & AE / floodway.

https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd

Could try using that layer and symbolizing by both field zone & zone subtype.

sgambrel_Bouldercounty

Hi Laura,

Unfortuinately I can't use the data straight from FEMA because we modify it slightly in certain areas. I did notice that they use the two fields together for their symbology - I'm not exactly sure why, when just the subtype will do - but maybe that's just here and not the case across the entire US... Anyway, I've tried to do that as well and the Map Viewer doesn't allow the Zone_Subtype field as an additional field to use for symbology once the Fld_Zone field is selected.

Something I should mention is that I have similar behavior in Pro, not recognizing the blank values as valid values to symbolize. That nixes the strategy of creating a properly symbolized layer in Pro and sharing it online. I've asked a similar question in the Pro Community. I'm starting to think there's just something wonky / corrupt in the feature class.

I really appreciate your attempts to help here! Thank you!

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