循環內的R中的JSON文件的循環

Question

我想聚集一堆JSON文件到一個單一的三個來源和三年。儘管到目前爲止，我只能通過這種單調乏味的方式做到這一點，但我相信我能以更聰明，更優雅的方式來做到這一點。

json1 <- lapply(readLines("NYT_1989.json"), fromJSON) 
json2 <- lapply(readLines("NYT_1990.json"), fromJSON) 
json3 <- lapply(readLines("NYT_1991.json"), fromJSON) 
json4 <- lapply(readLines("WP_1989.json"), fromJSON) 
json5 <- lapply(readLines("WP_1990.json"), fromJSON) 
json6 <- lapply(readLines("WP_1991.json"), fromJSON) 
json7 <- lapply(readLines("USAT_1989.json"), fromJSON) 
json8 <- lapply(readLines("USAT_1990.json"), fromJSON) 
json9 <- lapply(readLines("USAT_1991.json"), fromJSON) 

jsonl <- list(json1, json2, json3, json4, json5, json6, json7, json8, json9) 

請注意，從1989年到1991年這三個文件的年份都是一樣的。任何想法？謝謝！

PS：每個文件中的數據示例：

{"date": "December 31, 1989, Sunday, Late Edition - Final", "body": "Frigid temperatures across much of the United States this month sent demand for heating oil soaring, providing a final upward jolt to crude oil prices. Some spot crude traded at prices up 40 percent or more from a year ago. Will these prices hold? Five experts on oil offer their views. That's assuming the economy performs as expected - about 1 percent growth in G.N.P. The other big uncertainty is the U.S.S.R. If their production drops more than 4 percent, prices could stengthen. ", "title": "Prospects;"} 
{"date": "December 31, 1989, Sunday, Late Edition - Final", "body": "DATELINE: WASHINGTON, Dec. 30 For years, experts have dubbed Czechoslovakia's spy agency the ''two Czech'' service. But he cautioned against euphoria. ''The Soviets wouldn't have relied on just official cooperation,'' he said. ''It would be surprising if they haven't unilaterally penetrated friendly services with their own agents, too.'' ", "title": "Upheaval in the East: Espionage;"} 
{"date": "December 31, 1989, Sunday, Late Edition - Final", "body": "SURVIVING the decline in the economy will be the overriding issue for 1990, say leaders of the county's business community. Successful Westchester business owners will face and overcome these risks and obstacles. Westchester is a land of opportunity for the business owner. ", "title": "Coping With the Economic Prospects of 1990"} 

Answer 1

在這裏你去：

require(jsonlite) 

filelist <- c("NYT_1989.json","NYT_1990.json","NYT_1991.json", 
       "WP_1989.json", "WP_1990.json","WP_1991.json", 
       "USAT_1989.json","USAT_1990.json","USAT_1991.json") 

newJSON <- sapply(filelist, function(x) fromJSON(readLines(x))) 

---

閱讀在短短的輸入文件中的每一行的body條目。

您問及如何只讀取JSON文件的子集。引用的文件數據實際上不是JSON格式。這是JSON喜歡的，因此我們必須將輸入修改爲fromJSON()才能正確讀取數據。我們將fromJSON()$body的結果解引用，僅提取body變量。

filelist <- c("./data/NYT_1989.json", "./data/NYT_1990.json") 
newJSON <- sapply(filelist, function(x) fromJSON(sprintf("[%s]", paste(readLines(x), collapse = ",")), flatten = FALSE)$body) 
newJSON 

結果

> filelist <- c("./data/NYT_1989.json", "./data/NYT_1990.json") 
> newJSON <- sapply(filelist, function(x) fromJSON(sprintf("[%s]", paste(readLines(x), collapse = ",")), flatten = FALSE)$body) 
> newJSON 
    ./data/NYT_1989.json                                                                                                                     
[1,] "Frigid temperatures across much of the United States this month sent demand for heating oil soaring, providing a final upward jolt to crude oil prices. Some spot crude traded at prices up 40 percent or more from a year ago. Will these prices hold? Five experts on oil offer their views. That's assuming the economy performs as expected - about 1 percent growth in G.N.P. The other big uncertainty is the U.S.S.R. If their production drops more than 4 percent, prices could stengthen. " 
[2,] "DATELINE: WASHINGTON, Dec. 30 For years, experts have dubbed Czechoslovakia's spy agency the ''two Czech'' service. But he cautioned against euphoria. ''The Soviets wouldn't have relied on just official cooperation,'' he said. ''It would be surprising if they haven't unilaterally penetrated friendly services with their own agents, too.'' "                                     
[3,] "SURVIVING the decline in the economy will be the overriding issue for 1990, say leaders of the county's business community. Successful Westchester business owners will face and overcome these risks and obstacles. Westchester is a land of opportunity for the business owner. "                                                     
    ./data/NYT_1990.json                                                                                                                     
[1,] "Blue temperatures across much of the United States this month sent demand for heating oil soaring, providing a final upward jolt to crude oil prices. Some spot crude traded at prices up 40 percent or more from a year ago. Will these prices hold? Five experts on oil offer their views. That's assuming the economy performs as expected - about 1 percent growth in G.N.P. The other big uncertainty is the U.S.S.R. If their production drops more than 4 percent, prices could stengthen. " 
[2,] "BLUE1: WASHINGTON, Dec. 30 For years, experts have dubbed Czechoslovakia's spy agency the ''two Czech'' service. But he cautioned against euphoria. ''The Soviets wouldn't have relied on just official cooperation,'' he said. ''It would be surprising if they haven't unilaterally penetrated friendly services with their own agents, too.'' "                                     
[3,] "GREEN4 the decline in the economy will be the overriding issue for 1990, say leaders of the county's business community. Successful Westchester business owners will face and overcome these risks and obstacles. Westchester is a land of opportunity for the business owner. " 

---

您可能會發現下面的應用教程有用：

• Datacamp: R tutorial on the Apply family of functions

我也推薦閱讀：

• R Inferno - 第4章 - 過矢量化

信任我，當我說這個在線免費本書對我幫助很大。它也證實我是一個多重場合的白癡:-)