[Gretl-devel] Re: jsongetb(): changed behaviour!

Hello all, A heads-up for anyone using the jsongetb() function, for turning a JSON string into a gretl bundle. Up till now, when jsongetb encountered a JSON array containing numeric values it constructed an array of strings (using sprintf on the numbers). This was not very nice, but seemed like the easiest thing to do since we were matching each JSON array to a gretl array, and gretl does not have an "array of scalars" type as such. New in git (not yet snapshots) we're converting numeric JSON arrays to gretl matrices -- vectors, to be precise, because although JSON arrays can be nested, JSON doesn't have a two-dimensional array as such. In case it's of concern to anyone, let me be a little more explicit. (1) JSON: { "x" : [1, 2, 3] } Old jsongetb gave x as an array of strings ("1", "2", "3"). New jsongetb gives x as a column vector {1, 2, 3}'. (2) JSON { "x" : [[1, 2, 3], [4, 5, 6]] } Old jsongetb gave x as an array of arrays, each element of which was an array of strings: ("1", "2", "3") and ("4", "5", "6") New jsongetb gives x as an array of matrices (column vectors), namely {1, 2, 3}' and {4, 5, 6}'. Clearly, this change will break hansl code expecting JSON numeric arrays to come through in the old way. This applies to the dbnomics addon and the (new, not really published) geoplot addon, but the current code for those packages has been modified to handle both cases. And we didn't find any current contributed function packages that rely on the old jsongetb behaviour. If anyone has "serious" code they're using that is broken by the change in git, please tell us! Further comment for experts: What about missing values? And JSON arrays of mixed type (since that's allowed, god help us)? We judge a JSON array to be numeric based on the type of its first element. If subsequent elements have a null value, or a string value of "." or "NA", they are taken to be gretl NAs. Otherwise mixed types provoke an error in jsongetb. Allin