how to merge all field in single array in php for web service

{   
 "active_date":[
        "2016-12-24",
        "2017-01-03",
        "2016-12-24",
        "2016-12-24"
    ],
    "product_name":[
        "Spaces",
        "Samsung Galaxy J7 (2016)",
        "Nike Air",
        "HP Laptops"
    ],
    "product_category":[
        "Other",
        "Electrical & Electronics",
        "Men",
        "Electrical & Electronics"
    ],
    "old_price":[
        "1295",
        "14000",
        "2200",
        "35000"
    ],
    "nprice":[
        "799.00",
        "12500.00",
        "1800.00",
        "33000.00"
    ],
    "t_sale":[
        0,
        0,
        0,
        0
    ],
    "t_return":[
        0,
        0,
        0,
        0
    ],
    "availablity":[
        "10",
        "47",
        "9",
        "8"
    ]

}