title: Importing multing multiple JSON files in R single dataframe
body: <p>Hei,
  I want to import JSON files from a folder to R data frame (as a single matrix). I have about 40000 JSON files with one observation each and different variable sizes.</p>
  <p>I tried following codes</p>
  <pre><code>library(rjson)
  jsonresults_all &lt;- list.files(&quot;mydata&quot;, pattern=&quot;*.json&quot;, full.names=TRUE)
   
  myJSON &lt;- lapply(jsonresults_all, function(x) fromJSON(file=x)) 
  
  myJSONmat &lt;- as.data.frame(myJSON)
  </code></pre>
  <p>I want my data frame something like (40000 observations (rows) and some 175 variables (column) with some variable values NA.
  But I get a single row containing each observation appended to the right.
  Many thanks for your suggesion.</p>