Compact but pretty JSON output in python?

Question

JSON is written either with indent=None (default) as a single line (unreadable to a human eye) or with ident=N with a newline after each comma.

Answer 1

I don't know of a tool that already does this, but it isn't hard to make one:

def compact(d):
    def tight(obj):
        return dumps(obj, separators=(',', ':'))
    print('{')
    for i, (k, v) in enumerate(d.items()):
        comma = ',' if i < len(d) else ''
        print(f' {tight(k)}:{tight(v)}{comma}')
    print('}')

For your example, this emits:

>>> compact(d)
{
 "cleanup":{"cpu":6936.780000000001,"wall":7822.319401979446},
 "finished":"2017-08-14 18:36:23",
 "init":{"cpu":1365.73,"wall":1380.7802910804749},
 "job":"timings",
 "run":{"cpu":953.6700000000001,"wall":8350.496850013733},
 "started":"2017-08-14 13:28:06",
}

Answer 2

This is not possible at this time, but when RFE: more compact pretty printing is implemented, this question will be answered by using python-rapidjson.