4 ms·

I was wondering what they meant by that term as well. Does every JSON document in the array have to have the exact same structure (including the ordering of key

• kbouck 4y ago
  It generally means an sequence/array of flat json objects, each key represents a column name, and the value representing the row value for that column. Nested json can also be "flattened". > "... ordering of key-value pairs" order of appearance of key-value pairs in input does not matter. > "... if row #100 introduces a new key-value pair" this is sparse data. miller handles this with the "unsparsify" verb: $ cat in.json { "a": 1, "b": 2 } { "a": 3, "b": 4 } { "a": 5, "b": 6, "c": 7 } without unsparsify: $ cat in.json | mlr --j2p cat a b 1 2 3 4 a b c 5 6 7 with unsparsify: $ cat in.json | mlr --j2p unsparsify then cat a b c 1 2 - 3 4 - 5 6 7 unsparsify can also set default values: $ cat in.json | mlr --j2p unsparsify --fill-with 0 then cat a b c 1 2 0 3 4 0 5 6 7 > "... What if the value for a key is an array?" Array value treatment seems to depend on output format. for output types that can represent arrays, they are preserved: $ cat in-array.json { "a": [0,1,2], "b": [5,6,7] } { "a": [3,4,5], "b": [8,9,0] } $ cat in-array.json | mlr --jsonl cat {"a": [0, 1, 2], "b": [5, 6, 7]} {"a": [3, 4, 5], "b": [8, 9, 0]} for formats like csv/fixed-width, arrays are flattened into columns, one for each array element: $ cat in-array.json | mlr --j2p cat a.1 a.2 a.3 b.1 b.2 b.3 0 1 2 5 6 7 3 4 5 8 9 0 flatten separator can also be set: $ cat in-array.json | mlr --j2p --flatsep _ cat a_1 a_2 a_3 b_1 b_2 b_3 0 1 2 5 6 7 3 4 5 8 9 0