删除PHP数组中的逗号以进行JSON格式化

I'm outputting a json formatted array. Where I have the address fields and Market fields separated by commas I want to remove commas if a field doesn't exist so I don't end up with empty spaces with commas. I had a go below with implode but that doesn't seem to work... what is the correct way of doing this?I'm outputting a json formatted array. Where I