javascript - .arff格式的json怎么写

Question

我有以下 json 文件。

[
    {
        "y": 1.544937286376953, 
        "x": 0.0736468505859375, 
        "z": 10.19739440917969, 
        "timestamp": 1413232199331.14
    }, 
    {
        "y": 2.492466888427734, 
        "x": 0.7253915405273438, 
        "z": 11.33457962036133, 
        "timestamp": 1413232199831.21
    }
]

并且此列表中的两个对象都转化为高值(value)。类似于下面的天气示例，例如这两个对象是:

{
    "y": 1.544937286376953, 
    "x": 0.0736468505859375, 
    "z": 10.19739440917969, 
    "timestamp": 1413232199331.14
}

和

{
    "y": 2.492466888427734, 
    "x": 0.7253915405273438, 
    "z": 11.33457962036133, 
    "timestamp": 1413232199831.21
}

如果它们同时出现，则将其他属性设置为例如 Velocity 到 High。

我怎样才能把它写成像下面的天气例子:

@relation weather

@attribute outlook {sunny, overcast, rainy}
@attribute temperature numeric
@attribute humidity numeric
@attribute windy {TRUE, FALSE}
@attribute play {yes, no}

@data
sunny,85,85,FALSE,no
sunny,80,90,TRUE,no

我的属性在哪里是对象列表。

我的属性是这样的@attribute accelerator [{numeric,numeric,numeric},{numeric, numeric,numeric}]

有人知道我该怎么办吗？我的问题真的有意义吗？

Answer 1

在我看来你想做两件事:

1. 将 JSON 数据转换为 .arff
2. 将复合属性写入arff文件

我不知道 arff 文件是否支持#2。

这是一些将 JSON 转换为 arff 的代码(#1)在 R 中:

library(RWeka)
library(rjson)


json = rjson::fromJSON('[{
         "y": 1.544937286376953, 
         "x": 0.0736468505859375, 
         "z": 10.19739440917969, 
         "timestamp": 1413232199331.14
     }, 
     {
         "y": 2.492466888427734, 
         "x": 0.7253915405273438, 
         "z": 11.33457962036133, 
         "timestamp": 1413232199831.21
     }]')

str(json) # show internal representation

# replace nulls, optional
json <- lapply(json, function(x) {
        x[sapply(x, is.null)] <- NA
        unlist(x)
})

# convert to data frame
mydf <- data.frame(do.call("rbind", json))

# add some more attributes. I've just made up this business logic
mydf["accelerator"] = sqrt(mydf$x^2 + mydf$y^2 + mydf$z^2)
# here the new "accelerator" attribute is high if it is higher than 11    
mydf["accelerator_high"] = ifelse(mydf["accelerator"]<=11,"No","Yes")

RWeka::write.arff(mydf, "myfile.arff")

生成的 arff 文件:

@relation R_data_frame

@attribute y numeric
@attribute x numeric
@attribute z numeric
@attribute timestamp numeric
@attribute accelerator numeric
@attribute accelerator_high string

@data
1.544937,0.073647,10.197394,1413232199331.13984,10.314025,No
2.492467,0.725392,11.33458,1413232199831.209984,11.628038,Yes