如何在R中反规范化嵌套列表? [英] How to denormalize nested list in R?

问题描述

我想找到一种清晰易读的方式将类似src的结构(从JSON解析，这就是为什么有大量嵌套列表的原因)转换成类似dst的结构的方式.

I'd like to find a clean and readable way to convert a structure like src (parsed from JSON, that's why there are a ton of nested lists) to one like dst.

src <- list(
    sessions=list(
        list(
            statistics=list(
                list(
                    list(
                        round=0,
                        diff=3,
                        saldo=3
                    ),
                    list(
                        round=1,
                        diff=-1,
                        saldo=2
                    ),
                    list(
                        round=2,
                        diff=-1,
                        saldo=1
                    )
                ),
                list(
                    list(
                        round=0,
                        diff=-1,
                        saldo=-1
                    )
                )
            ),
            sessionProp="sv1"
        ),
        list(
            statistics=list(
                list(
                    list(
                        round=0,
                        diff=4,
                        saldo=4
                    )
                ),
                list(
                    list(
                        round=0,
                        diff=2,
                        saldo=2
                    )
                )
            ),
            sessionProp="sv2"
        )
    ),
    packageProps=list(
        rules=list(
            list(
                name="Ruleset 1",
                ruleProp="rv1"
            ),
            list(
                name="Ruleset 2",
                ruleProp="rv2"
            )
        ),
        packageProp="package prop value"
    )
)

dst <- data.frame(
    round=c(0,1,2,0,0,0),
    diff=c(3,-1,-1,-1,4,2),
    saldo=c(3,2,1,-1,4,2),
    sessionProp=c("sv1","sv1","sv1","sv1","sv2","sv2"),
    ruleProp=c("rv1","rv1","rv1","rv2","rv1","rv2")
)

两个会话在statistics列表中都有两个元素.这些元素对应于rules列表packageProps中的两个元素.这是与几乎直接非正规化的唯一区别.

Both sessions have two elements in statistics list. Those correspond to two elements in rules list packageProps. That's the only difference from pretty much direct denormalization.

推荐答案

在更大的列表上试一试(我假设有更多或更大的版本)

Give this a shot on the larger list (I'm assuming there are either more or larger versions of this):

do.call(rbind.data.frame, lapply(1:length(src$sessions), function(i) {
  dat <- do.call(rbind.data.frame, 
                 lapply(unlist(src$sessions[[i]]$statistics, recursive=FALSE), 
                        rbind.data.frame))
  dat$sessionProp <- src$sessions[[i]]$sessionProp
  dat$ruleProp <- src$packageProps$rules[[i]]$ruleProp
  dat
}))

##     round diff saldo sessionProp ruleProp
## 2       0    3     3         sv1      rv1
## 21      1   -1     2         sv1      rv1
## 22      2   -1     1         sv1      rv1
## 23      0   -1    -1         sv1      rv1
## 24      0    4     4         sv2      rv2
## 211     0    2     2         sv2      rv2

如果需要，可以删除行名称.如果您使用dplyr的bind_rows与do.call(rbind…，则只会节省一些输入时间，而且还会自动对行名进行定位.不过，我希望其他人可以找到更好的解决方案.

You can nuke the row names if desired. If you use dplyr's bind_rows vs do.call(rbind… it only saves a teensy bit of typing, but will also auto-nuke the row names. I'm hoping others can find an even more optimal solution, though.

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