JSON文字列をRリストに解析する

Question

enter code hereこんにちは私はJSONファイルを持っていて、それをリストで解析したいと考えています。私はそれに特定の文字列を持つ行だけを解析できるのだろうか？例えば

{"app":15c,"device_carrier":"Verizon Wireless"} 
{"app":15b,"device_carrier":"Verizon Wireless"} 
{"app":15a,"device_carrier":"Verizon Wireless"} 

と私は最後の行のリストを持ちたい"app":15a 持っている唯一の行を解析したい！（問題は、私は多くのデータを持っているし、私のコンピュータが解析できません全体JSONファイル、と私は唯一のアプリが必要）

Answer 1

あり、以下を最適化する方法があるが、それはあなたの場合には必要ではないかもしれません。

0：

library(jsonlite) 
library(dplyr) 

df <- data_frame() 
jsonlite::stream_in(file("/tmp/apps.json"), function(x) { df <<- bind_rows(df, filter(x, app=="15b")) }) 

私はのように見えるファイルを作りましたあなたが得るコードと

{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 
{"app":"15c","device_carrier":"Verizon Wireless"} 
{"app":"15b","device_carrier":"Verizon Wireless"} 
{"app":"15a","device_carrier":"Verizon Wireless"} 

ラン：

df 
## # A tibble: 13 × 2 
##  app device_carrier 
## <chr>   <chr> 
## 1 15b Verizon Wireless 
## 2 15b Verizon Wireless 
## 3 15b Verizon Wireless 
## 4 15b Verizon Wireless 
## 5 15b Verizon Wireless 
## 6 15b Verizon Wireless 
## 7 15b Verizon Wireless 
## 8 15b Verizon Wireless 
## 9 15b Verizon Wireless 
## 10 15b Verizon Wireless 
## 11 15b Verizon Wireless 
## 12 15b Verizon Wireless 
## 13 15b Verizon Wireless