JSON to dataframe input and output

[mihirparadkar]

Could dataframes be read from and output to JSON? I know that pandas and R do it and it's a very universal format. Here are some simple implementations of readjson and writejson using the JSON.jl package.
readjson:

using JSON
using Lazy
using DataFrames

function readjson(filename::String)
  rawdata = JSON.parsefile(filename)
  names = @as file rawdata begin
                map(keys,file)
                vcat([[i...] for i in file]...)
                unique(file)
          end
  df = DataFrame()
  for name in names
    df[symbol(name)] = map(rawdata) do obj
      haskey(obj,name) ? obj[name] : NA
    end
    for i in 1:length(df[symbol(name)])
      if df[symbol(name)][i] == nothing
        df[symbol(name)][i] = NA
      end
    end
  end
  return df
end

and writejson:

using JSON
using DataFrames

function df2json(df::DataFrame)
  len = length(df[:,1])
  indices = names(df)
  jsonarray = [Dict([string(index)=> (isna(df[index][i])? nothing : df[index][i])
                                                    for index in indices])
                                                          for i in 1:len]
  return JSON.json(jsonarray)
end

function writejson(path::String,df::DataFrame)
  f = open(path,"w")
  write(f,df2json(df))
  close(f)
end

[mihirparadkar]

The readjson code works for data of the format

[
 {"name1":value11 , "name2":value21 ...},
 {"name1":value12 , "name2":value22 ...},
 ...
]

[rawls238]

@mihirparadkar why not put up a PR for this?

[bkamins]

Closing as this is handled by JSONTables.jl now thanks to @quinnj.