ARROW-4859: [GLib] Add garrow_numeric_array_mean()

[shiro615]

No description provided.

[kou]

Thanks!
Could you check my comments?

[kou]

Could you use 0.0 for gdouble?

[shiro615]

I've fixed it.

[kou]

assert_equal isn't suitable for floating point number. Because floating point number may have an error.
Could you use assert_in_delta https://www.rubydoc.info/gems/test-unit/Test/Unit/Assertions#assert_in_delta-instance_method instead?

[shiro615]

Thank you for pointing out. I've fixed it.

[mrkn]

Should it be NaN?

[kou]

If we use NaN, std::numeric_limits<double>::signaling_NaN() https://en.cppreference.com/w/cpp/types/numeric_limits/signaling_NaN will be better.
But I don't think this is required. Because we indicate whether error is occurred by error argument. Users should check error instead of checking return value for error check.

[kou]

If @shiro615 changes this before I merge, I'll accept the change. :-)

[shiro615]

Users can check error argument. I want to use 0.0.

[kou]

OK.

[kou]

+1
I'll merge this when test is passed.

[kou]

CI failure is unrelated. I'll merge this.

https://travis-ci.org/apache/arrow/jobs/506259901 is Plasma related failure:

=================================== FAILURES ===================================
_______________________________ test_plasma_list _______________________________

    @pytest.mark.plasma
    def test_plasma_list():
        import pyarrow.plasma as plasma
    
        with plasma.start_plasma_store(
                plasma_store_memory=DEFAULT_PLASMA_STORE_MEMORY) \
                as (plasma_store_name, p):
            plasma_client = plasma.connect(plasma_store_name)
    
            # Test sizes
            u, _, _ = create_object(plasma_client, 11, metadata_size=7, seal=False)
            l1 = plasma_client.list()
            assert l1[u]["data_size"] == 11
            assert l1[u]["metadata_size"] == 7
    
            # Test ref_count
            v = plasma_client.put(np.zeros(3))
            l2 = plasma_client.list()
            # Ref count has already been released
            assert l2[v]["ref_count"] == 0
            a = plasma_client.get(v)
            l3 = plasma_client.list()
            assert l3[v]["ref_count"] == 1
            del a
    
            # Test state
            w, _, _ = create_object(plasma_client, 3, metadata_size=0, seal=False)
            l4 = plasma_client.list()
            assert l4[w]["state"] == "created"
            plasma_client.seal(w)
            l5 = plasma_client.list()
            assert l5[w]["state"] == "sealed"
    
            # Test timestamps
            t1 = time.time()
            x, _, _ = create_object(plasma_client, 3, metadata_size=0, seal=False)
            t2 = time.time()
            l6 = plasma_client.list()
>           assert math.floor(t1) <= l6[x]["create_time"] <= math.ceil(t2)
E           assert 1552568478 <= 1552568477
E            +  where 1552568478 = <built-in function floor>(1552568478.0022461)
E            +    where <built-in function floor> = math.floor

../../pyarrow-test-3.6/lib/python3.6/site-packages/pyarrow/tests/test_plasma.py:1070: AssertionError
----------------------------- Captured stderr call -----------------------------
I0314 13:01:17.901209 19953 store.cc:1093] Allowing the Plasma store to use up to 0.1GB of memory.
I0314 13:01:17.901417 19953 store.cc:1120] Starting object store with directory /dev/shm and huge page support disabled

@pcmoritz @robertnishihara Could you fix this Plasma failure?

https://ci.appveyor.com/project/ApacheSoftwareFoundation/arrow/builds/23071125/job/s8iwxmf9hddh3q07 will be fixed by #3905.

[kou]

@pcmoritz @robertnishihara I've opened https://issues.apache.org/jira/browse/ARROW-4877 .