make JSON files smaller by limiting the precision

[jgriesfeller]

attempt to fix #366

[codecov]

Codecov Report

Merging #499 (2272172) into main-dev (25aea64) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 2272172 differs from pull request most recent head 5ee4b3e. Consider uploading reports for the commit 5ee4b3e to get more accurate results

@@             Coverage Diff              @@
##           main-dev     #499      +/-   ##
============================================
+ Coverage     76.64%   76.65%   +0.01%     
============================================
  Files            97       97              
  Lines         17357    17365       +8     
============================================
+ Hits          13304    13312       +8     
  Misses         4053     4053              

Flag	Coverage Δ
unittests	76.65% <100.00%> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
pyaerocom/_lowlevel_helpers.py	82.26% <100.00%> (+0.37%)	⬆️

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[avaldebe]

please conside the following changes

• use np.round instead of round
• use comprehensions instead if create/modify loops
• add a test tat covers this new test that asserts the round_floats functionality

  assert round_floats(16.055, 2) == 16.055
  assert round_floats([16.055], 2) == [16.055]
  assert round_floats({"value":16.055}, 2) == {"value":16.055}

[avaldebe]

This is what I mean regarding the usage of comprehensions instead of create/modify loops

    if isinstance(in_data, (float, np.float)):
        return np.round(in_data, precision)
    if isinstance(in_data, (list, tuple)):
        return [round_floats(v, precision=precision) for v in in_data]
    if isinstance(in_data, dict):
        return {k:round_floats(v, precision=precision) for k, v in in_data.items()}
    return in_data # or raise a ValueError

I never meant to say that the if isinstance logic should be folded into the comprehension

[avaldebe]

Thanks for the changes.
Could you also ads some tests that assert on the desired functionality.

assert round_floats(16.055, 2) == 16.06
assert round_floats([16.055], 2) == [16.06]
assert round_floats({"value":16.055}, 2) == {"value":16.06}

[avaldebe]

👍 ship it

[jgriesfeller]

Will merge as soon as CI is finished