将 JSON 转换为 CSV（数据框）时的问题答案

【问题标题】：Problems in converting JSON to CSV(data frame)将 JSON 转换为 CSV（数据框）时的问题
【发布时间】：2016-07-05 23:41:42
【问题描述】：

我正在尝试使用 R 中的 jsonlite 包将以下 JSON 文件转换为 CSV（数据框）。我无法这样做。我正在寻找一种可以解析任何复杂性和嵌套的JSON 的通用方法？

library(jsonlite)
fromJSON(json_file)

JSON 文件：

{
 "IRD": {
 "INTV": {
 "INTVStatus": "SERV_HST",
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "1" 
},
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "2" 
},
"RD": {
 "U": "Vrms",
"BEV": "231.0000",
"Val": "231.0000",
"RV": "231",
"port": "3" 
},
".attrs": {
 "GatewayCollectedTime": "2015-12-21T12:05:02.257-05:00",
"INTVSequenceNumber": "47112",
"BlockSequenceNumber": "0",
"EndTime": "2015-12-21T10:00:00.000-05:00" 
} 
},
"INTV": {
 "INTVStatus": "SERV_HST",
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "1" 
},
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "2" 
},
"RD": {
 "U": "Vrms",
"BEV": "231.0000",
"Val": "231.0000",
"RV": "231",
"port": "3" 
},
".attrs": {
 "GatewayCollectedTime": "2015-12-21T12:05:02.257-05:00",
"INTVSequenceNumber": "47113",
"BlockSequenceNumber": "0",
"EndTime": "2015-12-21T11:00:00.000-05:00" 
} 
},
"INTV": {
 "INTVStatus": "SERV_HST",
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "1" 
},
"RD": {
 "U": "kWh",
"BEV": "0.0379",
"Val": "0",
"RV": "0",
"port": "2" 
},
"RD": {
 "U": "Vrms",
"BEV": "231.0000",
"Val": "231.0000",
"RV": "231",
"port": "3" 
},
".attrs": {
 "GatewayCollectedTime": "2015-12-21T12:05:02.257-05:00",
"INTVSequenceNumber": "47114",
"BlockSequenceNumber": "0",
"EndTime": "2015-12-  21T12:00:00.000-05:00" 
} 
},
".attrs": {
 "NumberINTVs": "3",
"EndTime": "2015-12-21T12:00:00.000-05:00",
"StartTime": "2015-   12-21T09:00:00.000-05:00",
"INTVLength": "60" 
} 
},
".attrs": {
 "Version": "2.0",
"DocumentID": "aebjjjjd-59de-4405-ac0b-50e33b0b4f4b-1",
"JobID": "3354",
"ExportID": "aeb5bf7d-59de-4405-er0b-50e33b0b4f4b",
"RunID": "20430452",
"CreationTime": "2015-12-21T13:55:00.807-05:00",
"StartTime": "2015-12-21T09:55:00.000-  05:00",
"EndTime": "2015-12-21T13:55:00.000-05:00" 
} 
}

【问题讨论】：

“我正在寻找一种可以解析任何复杂和嵌套的 JSON 的通用方法？” ...这要求很多，因为有时JSON 没有明显的表格等价物，至少没有做出一些决定。
你能在 R 中推荐一些可以帮助解析上述 JSON 文件的东西

标签： json r csv

【解决方案1】：

简单地通过其多重嵌套结构，考虑逐级解析JSON（作业/文档、INTV、RD和attrs），然后将它们绑定到数据帧中：

library(jsonlite)

# READ IN JSON FILE INTO NESTED LIST
ird <- do.call(rbind,
               lapply(paste(
                      readLines("JSONFile.json", warn=FALSE),
                      collapse=""), 
               jsonlite::fromJSON))    
# JOB
job <- list(ird[[2]])

# INVSTATUS
intvstatus <- lapply(1:3, function(i) ird[[1]][i]$INTV$INTVStatus)

# RDs (nested lapply for three RDs per three INTVs)
rds <- lapply(1:3, function(i)
                   do.call(rbind, lapply(2:4, 
                                  function(j) ird[[1]][i]$INTV[j]$RD)
                           )
              )    
# ATTRS
attrs <- lapply(1:3, function(i) ird[[1]][i]$INTV$.attrs)

# BINDING EACH LIST TO FINAL DF (rep() to repeat for each 9 RDs)
df <- data.frame(do.call(rbind, rep(job,9)),
                 INTVStatus = do.call(rbind, rep(intvstatus, 3)),
                 do.call(rbind, rds),
                 do.call(rbind, rep(attrs,3)),
                 stringsAsFactors=FALSE)
# TO FLATTEN LISTS OUTPUT FROM DO CALLS
df <- data.frame(lapply(df, as.character), stringsAsFactors=FALSE)

# OUTPUT TO CSV
write.csv(df, 'Output.csv')

【讨论】：