No Magnus ....
Here is what i have on my filter
geoip {
source => "ip"
target => "geoip"
database => "/etc/logstash/GeoLiteCity.dat"
add_field => [ "[geoip][coordinates]", "%{[geoip][longitude]}" ]
add_field => [ "[geoip][coordinates]", "%{[geoip][latitude]}"  ]
}
mutate {
convert => [ "[geoip][coordinates]", "float"]
}
but nothing happen .. Logstash operate normally but coordinate no shown ... i am not sure this is correct or not.