Only display Top 10% of values ArcMap

This is simple to do if your feature class is in a sql geodatabase - you can just set a definition query to select literally just the top 10 percent of values:

Value IN (SELECT TOP(10) PERCENT Value from gisse.DBO.MyPoints order by Value Desc)

just change Value to your field name (it appears 3 times in the code above), and change the gisse.DBO.MyPoints to reference your data source.

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On the other hand, if your feature class is in a file geodatabase it's a bit more complicated, but it can be done. The way I did it is as follows:

I created a new field called TenPC and opened the Field Calculator

Select the Python Parser and click on "Show Codeblock" and use add this code:

x = "MyPoints"
f = "Value"
tpc = (int(arcpy.GetCount_management(x)[0])/10) + 1
y = list()
with arcpy.da.SearchCursor(x,f) as cursor:
    for row in cursor:
        y.append(row[0])
z = sorted(y,reverse=True)[:tpc]

def top_ten_pc(fieldval):
    if fieldval in z:
        return True
    else:
        return False

And this expression:

top_ten_pc(!Value!)

Changing x = "MyPoints" to reference your layer, and f = "Value" to reference the field name you're filtering on, and !Value! to also reference the field name.

Click OK to calculate the field. Now in your new field you should see lots of 0 and 1 values. Any feature with a 1 is in your top 10 percent of values.

You can now write a definition query to display only these features

TenPC = 1

Note - my Python is very rusty and I may be overthinking this, so there may be far more efficient ways to do what I've described above!