Convert JSON into CSV in R programming - json

Question

I have JSON of the form:
{"abc":
{
"123":[45600],
"378":[78689],
"343":[23456]
}
}
I need to convert above format JSON to CSV file in R.
CSV format :
ds y
123 45600
378 78689
343 23456
I'm using R library rjson to do so. I'm doing something like this:
jsonFile <- fromJSON(file=fileName)
json_data_frame <- as.data.frame(jsonFile)
but it's not doing the way I need it.

Answer 1

You can use jsonlite::fromJSON to read the data into a list, though you'll need to pull it apart to assemble it into a data.frame:
abc <- jsonlite::fromJSON('{"abc":
{
"123":[45600],
"378":[78689],
"343":[23456]
}
}')
abc <- data.frame(ds = names(abc[[1]]),
y = unlist(abc[[1]]), stringsAsFactors = FALSE)
abc
#> ds y
#> 123 123 45600
#> 378 378 78689
#> 343 343 23456

Answer 2

I believe you got the json file reader - fromJSON function right.
df <- data.frame( do.call(rbind, rjson::fromJSON( '{"a":true, "b":false, "c":null}' )) )

Answer 3

The code below gets me Google's Location History (json) archive from https://takeout.google.com. This is if you have enabled a 'Timeline' (location tracking) in Google Maps on your cell. Credit to http://rpubs.com/jsmanij/131030 for the original code. Note that json files like this can be quite large and plyr::llply is so much more efficient than lapply in parsing a list. Data.table gives me the more efficient 'rbindlist' to take the list to a data.table. Google logs between 350 to 800 GPS calls each day for me! A multi-year location history is converted to quite a sizeable list by 'fromJSON':
format(object.size(doc1),units="MB")
[1] "962.5 Mb"
I found 'do.call(rbind..)' un-optimized. The timestamp, lat, and long needed some work to be useful to Google Earth Pro, but I am getting carried away. At the end, I use 'write.csv' to take a data.table to CSV. That is all the original OP wanted here.
ts lat long latitude longitude
1: 1416680531900 487716717 -1224893214 48.77167 -122.4893
2: 1416680591911 487716757 -1224892938 48.77168 -122.4893
3: 1416680668812 487716933 -1224893231 48.77169 -122.4893
4: 1416680728947 487716468 -1224893275 48.77165 -122.4893
5: 1416680791884 487716554 -1224893232 48.77166 -122.4893
library(data.table)
library(rjson)
library(plyr)
doc1 <- fromJSON(file="LocationHistory.json", method="C")
object.size(doc1)
timestamp <- function(x) {as.list(x$timestampMs)}
timestamps <- as.list(plyr::llply(doc1$locations,timestamp))
timestamps <- rbindlist(timestamps)
latitude <- function(x) {as.list(x$latitudeE7)}
latitudes <- as.list(plyr::llply(doc1$locations,latitude))
latitudes <- rbindlist(latitudes)
longitude <- function(x) {as.list(x$longitudeE7)}
longitudes <- as.list(plyr::llply(doc1$locations,longitude))
longitudes <- rbindlist(longitudes)
datageoms <- setnames(cbind(timestamps,latitudes,longitudes),c("ts","lat","long")) [order(ts)]
write.csv(datageoms,"datageoms.csv",row.names=FALSE)