将json格式的列转换为新的数据框 [英] converting a column in json format into a new data frame
问题描述
我有一个 csv文件,其中一列为 json格式.
I have a csv file and one of the column is in json format.
json格式的特定列如下所示:
that particular column in json format looks like this:
{"title":" ","body":" ","url":"thedailygreen print this healthy eating eat safe Dirty Dozen Foods page all"}
我已经在R中使用read.csv读取了此文件.现在,如何从此列创建一个新的数据框,该字段的名称应为title,body和url.
I have read this file using read.csv in R. Now, how to I create a new data frame from this column which should have field names as title, body and url.
推荐答案
您可以使用包RJSONIO解析列值,例如:
You can use package RJSONIO to parse the column values, e.g. :
library(RJSONIO)
# create an example data.frame with a json column
cell1 <- '{"title":"A","body":"X","url":"http://url1.x"}'
cell2 <- '{"title":"B","body":"Y","url":"http://url2.y"}'
cell3 <- '{"title":"C","body":"Z","url":"http://url3.z"}'
df <- data.frame(jsoncol = c(cell1,cell2,cell3),stringsAsFactors=F)
# parse json and create a data.frame
res <- do.call(rbind.data.frame,
lapply(df$jsoncol, FUN=function(x){ as.list(fromJSON(x))}))
> res
title body url
A X http://url1.x
B Y http://url2.y
C Z http://url3.z
: 上面的代码假定所有单元格仅包含标题,正文和url.如果json单元中可以有其他属性,请改用以下代码:
N.B. : the code above assumes all the cells contains title, body and url only. If there can be other properties in the json cells, use this code instead :
vals <- lapply(df$jsoncol,fromJSON)
res <- do.call(rbind, lapply(vals,FUN=function(v){ data.frame(title=v['title'],
body =v['body'],
url =v['url']) }))
编辑(根据评论):
我已使用以下代码读取文件:
I've read the file using the following code :
df <- read.table(file="c:\\sample.tsv",
header=T, sep="\t", colClasses="character")
然后使用以下代码进行解析:
then parsed using this code :
# define a simple function to turn NULL to NA
naIfnull <- function(x){if(!is.null(x)) x else NA}
vals <- lapply(df$boilerplate,fromJSON)
res <- do.call(rbind,
lapply(vals,FUN=function(v){ v <- as.list(v)
data.frame(title=naIfnull(v$title),
body =naIfnull(v$body),
url =naIfnull(v$url)) }))
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