What's the grammatical function of こと in this sentence?


> 電車の中などで見る最近の若い者の態度の悪い **こと** 、全く不愉快極まる。

I believe 全く不愉快極まる is the predicate and the rest before the comma is the
subject, but I don't understand how the two parts are connected by こと. Could
you help me figure it out?




You could imagine a similar sentence that has a は or が after the こと. こと is
serving as the head of the relative clause which comes before it, and is
basically a noun, which is why it can serve as the subject (and accordingly
why it can be marked by subject/topic marking particles like が and は).

One way to analyze your sentence is that the lack of particle is due to one of
は or が being dropped, since dropping of particles is possible in informal
Japanese.

However, I think it’s best to think of it as a third way to mark subjects:
with nothing, or rather, with a pause (which is why there is a comma).

I say this because it has a very slightly different nuance; in particular,
it’s the most neutral way to put the sentence. Using が makes it feel like
you’re either explicitly marking it as new information or trying to focus it,
while は makes it feel like you’re trying to switch the topic to it, which may
not be appropriate depending on how the sentence fits into the overall topic
flow of the larger discourse — for example, a following sentence of これに関して、政府
**は** (…) works better when your sentence doesn’t have a は in it and the whole
point of bringing up the poor behavior thing was to talk about the government
and its response. That is, the _lack_ of topic in the first sentence prepares
the listener for the real topic to come.

