将R数据帧写入信息报可读的JSON文件

Question

I'm trying to write a dataframe to a JSON format that infogram can recognise, to automate live updates. I've been using R and the jsonlite package.

For example:

df <- data.frame(X = c(1,2,3),
                 Y = c(5,7,8))
df

#  X Y
#1 1 5
#2 2 7
#3 3 8

I've come up with:

require(jsonlite)

rbind(as.matrix(t(names(df))), 
      as.matrix(df)) %>% 
  toJSON(pretty = T) # or write_json(filename, pretty = T) to write straight to file

Which results in:

[
  ["X", "Y"],
  ["1", "5"],
  ["2", "7"],
  ["3", "8"]
] 

The desired format is essentially the above but enclosed in an extra pair of square brackets (note the first array consists of column headings, then each subsequent array is an observation).

[[
  ["X", "Y"],
  ["1", "5"],
  ["2", "7"],
  ["3", "8"]
]]

Is there an easy way to achieve this? Thanks

Answer 1

require(jsonlite)

## The data.frame
df <- data.frame(X = c(1,2,3),
                 Y = c(5,7,8))

Now you could modify your object to be a list then you'll get the same list item in your json output:

mat <- list(rbind(as.matrix(t(names(df))), as.matrix(df)))

now with the extra bracket you want:

toJSON(mat, pretty = T)