For a db with: "key1":"valuex" "key2":"valuey" "key3":"valueString" avg(self) should return (valuex +valuey)/2. String values will be ignored.
For a db with:
"key1":"valuex"
"key2":"valuey"
"key3":"valueString"
avg(self) should return (valuex +valuey)/2. String values will be ignored.