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我一直在尝试学习 R，并且我有一个包含单行 JSON 对象的 JSON 文件，每个对象都有一个帐户数据数组。我要做的是解析每一行，然后从解析的 JSON 对象中获取 JSON 数组，提取帐户类型和金额。但我的问题是我不知道如何最好地把这两个属性拉出来。

我尝试使用 dplyr 包从我的每条 JSON 行中提取“accountHistory”，但出现控制台错误。当我尝试：

select(JsonAcctData, "accountHistory.type", "accountHistory.amount")

发生的情况是，我的代码只返回每行类型和金额的最后一个帐户。

现在我的代码正在写入一个 csv 文件，我可以看到我需要的所有数据，但我只想删除 ext

library("rjson")
library("dplyr")

parseJsonData <- function (sourceFile, outputFile) 
{
  #Get all total lines in the source file provided
  totalLines <- readLines(sourceFile)

  #Clean up old output file
  if(file.exists(outputFile)){
    file.remove(outputFile)
  }

  #Loop over each line in the sourceFile, 
  #parse the JSON and append to DataFrame
  JsonAcctData <- NULL
  for(i in 1:length(totalLines)){
    jsonValue <- fromJSON(totalLines[[i]])
    frame <- data.frame(jsonValue)
    JsonAcctData <- rbind(JsonAcctData, frame)
  }

  #Try to get filtered data
  filteredColumns <- 
    select(JsonAcctData, "accountHistory.type", "accountHistory.amount")
  print(filteredColumns)

  #Write the DataFrame to the output file in CSV format
  write.csv(JsonAcctData, file = outputFile)

}

测试 JSON 文件数据：

{"name":"Test1", "accountHistory":[{"amount":"107.62","date":"2012-02- 
  02T06:00:00.000Z","business":"CompanyA","name":"Home Loan Account 
  6220","type":"payment","account":"11111111"}, 
  {"amount":"650.88","date":"2012-02- 
  02T06:00:00.000Z","business":"CompanyF","name":"Checking Account 
  9001","type":"payment","account":"123123123"}, 
  {"amount":"878.63","date":"2012-02- 
  02T06:00:00.000Z","business":"CompanyG","name":"Money Market Account 
  8743","type":"deposit","account":"123123123"}]}
  {"name":"Test2", "accountHistory":[{"amount":"199.29","date":"2012-02-            
  02T06:00:00.000Z","business":"CompanyB","name":"Savings Account 
  3580","type":"invoice","account":"12312312"}, 
  {"amount":"841.48","date":"2012-02- 
  02T06:00:00.000Z","business":"Company","name":"Home Loan Account 
  5988","type":"payment","account":"123123123"}, 
  {"amount":"116.55","date":"2012-02- 
  02T06:00:00.000Z","business":"Company","name":"Auto Loan Account 
  1794","type":"withdrawal","account":"12312313"}]}

我期望得到一个仅包含帐户类型和每个帐户中持有的金额的 csv。

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1 回答 1

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这是一种使用regex(in base R)的方法

# read json 
json <- readLines('test.json', warn = FALSE)
# extract with regex
amount <- grep('\"amount\":\"\\d+\\.\\d+\"', json, value = TRUE)
amount <- as.numeric(gsub('.*amount\":\"(\\d+\\.+\\d+)\".*', '\\1', amount, perl = TRUE))
type   <- grep('\"type\":\"\\w+\"', json, value = TRUE)
type   <- gsub('.*type\":\"(\\w+)\".*', '\\1', type, perl = TRUE)
# output
data.frame(type, amount)
#         type amount
# 1    payment 107.62
# 2    payment 650.88
# 3    deposit 878.63
# 4    invoice 199.29
# 5    payment 841.48
# 6 withdrawal 116.55
于 2019-01-17T21:23:10.003 回答