ARROW-1557 [Python] Validate names length in Table.from_arrays

[TomAugspurger]

We now raise a ValueError when the length of the names doesn't match
the length of the arrays.

In [1]: import pyarrow as pa

In [2]: pa.Table.from_arrays([pa.array([1, 2]), pa.array([3, 4])], names=['a', 'b', 'c'])
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-2-cda803f3f774> in <module>()
----> 1 pa.Table.from_arrays([pa.array([1, 2]), pa.array([3, 4])], names=['a', 'b', 'c'])

table.pxi in pyarrow.lib.Table.from_arrays()

table.pxi in pyarrow.lib._schema_from_arrays()

ValueError: Length of names (3) does not match length of arrays (2)

This affected RecordBatch.from_arrays and Table.from_arrays.

[wesm]

+1, thanks @TomAugspurger!

[wesm]

Appears there is a test failure that was exposed by this patch, can you fix? https://travis-ci.org/apache/arrow/jobs/277580062#L9653

[wesm]

here's a fix to cherry pick wesm@965a560

[TomAugspurger]

Sure thing. While we have the chance, on https://github.com/apache/arrow/pull/1117/files#diff-434b799d30eaec7287bee5603a9c45beR318, should that be changed to if not K, since that's already len(arrays)? My intuition is that len is going to be pretty quick anyway, but thought I'd check.

[wesm]

if not K is probably better, feel free to make that change too

[wesm]

In case it's useful we have nightly dev builds

http://arrow.apache.org/install/index.html#nightly-development-builds

I'd like to get macOS nightlies set up also -- if this is of interest I have a Mac Mini running at home where we could set up a cron job.