There are no such places in Zurich HONESTLY! Sure you will find crazy people here and there but there are no rough areas like in English cities. I used to work in Kensington and the amount of muggings I witnessed on the Hammersmith road were shocking (a non rough area). Daylight robbing of occupants in expensive cars at traffic lights and traffic jams.

CH is really heaven when it comes to safety, don't let your guard down as dodgy things like rape in the train toilets have occured before. Mostly common sense stuff will keep you in good shape.