visualMap的categories为数值型字符串时，无法匹配series的data对应类目

[xiaotianlongxing]

One-line summary [问题简述]

echarts3，散点图，visualMap的categories为数值型字符串时，无法匹配series的data对应类目

Version & Environment [版本及环境]

• ECharts version [ECharts 版本]:echart3.4.0
• Browser version [浏览器类型和版本]:谷歌56.0.2896.3
• OS Version [操作系统类型和版本]:win7

Expected behaviour [期望结果]

正常显示

ECharts option [ECharts配置项]

option = {
    "xAxis": {
        "type": "value",
        "name": "salary"
    },
    "yAxis": {
        "type": "value",
        "name": "deposit"
    },
    "visualMap": [
        {
            "show": true,
            "dimension": 2,
            "categories": ["11","12"],
            "inRange": {
                "color": ["#ff6600","#9F79EE"]
            }
        }
    ],
    "series": [
        {
            "data": [
                [ "500.0","100.0","11"],
                ["4432.0","500.0","12"]
            ],
            "type": "scatter"
        }
    ]
}

Other comments [其他信息]