Accessing single value in field using ArcPy with ArcGIS Pro

Question

I'm pretty new to Python scripting (especially in ArcGIS). I would like to access a single element from a field and modify it. I understand that I can do this with cursors by searching the field column for the value (arcpy.da.SearchCursor) and then replacing it (arcpy.da.UpdateCursor), but this feels inefficient.

Is there a way to directly access an element without looping continuously?

Answer 1

As commented by @user2856 using a where_clause on your UpdateCursor is all that is needed.

If you have variables fc, fld and val set to a feature class, a field name in that feature class, and a value in a text field respectively then this should work to change the value to a new value of "X":

with arcpy.da.UpdateCursor(fc,fld,"{0} = '{1}'".format(fld,val)) as cursor:
    for row in cursor:
        row[0] = 'X'
        cursor.updateRow(row)