Issue training on ud-treebanks

[neetle]

Trying to train a treebank against ud-treebanks-v2.3/UD_English-EWT/en_ewt-ud-dev.conllu and I've noticed that all rows that have a head field with the value _ panic.

Any ideas on how to deal with this data within the library? Happy to submit a PR on any advice given.

# sent_id = answers-20111108072305AAPJTjj_ans-0005
# text = It's more compact, ISO 6400 capability (SX40 only 3200), faster lens at f/2 and the SX40 only f/2.7.
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	4	nsubj	4:nsubj	SpaceAfter=No
2	's	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	cop	4:cop	_
3	more	more	ADV	RBR	_	4	advmod	4:advmod	_
4	compact	compact	ADJ	JJ	Degree=Pos	0	root	0:root	SpaceAfter=No
5	,	,	PUNCT	,	_	8	punct	8:punct	_
6	ISO	iso	NOUN	NN	Number=Sing	8	compound	8:compound	_
7	6400	6400	NUM	CD	NumType=Card	6	nummod	6:nummod	_
8	capability	capability	NOUN	NN	Number=Sing	4	list	4:list	_
9	(	(	PUNCT	-LRB-	_	10	punct	10:punct|10.1:punct	SpaceAfter=No
10	SX40	SX40	PROPN	NNP	Number=Sing	8	parataxis	8:parataxis|10.1:nsubj	_
#dies on the following line
10.1	has	have	VERB	VBZ	_	_	_	8:parataxis	CopyOf=-1
11	only	only	ADV	RB	_	12	advmod	12:advmod	_
12	3200	3200	NUM	CD	NumType=Card	10	orphan	10.1:obj	SpaceAfter=No
13	)	)	PUNCT	-RRB-	_	10	punct	10:punct|10.1:punct	SpaceAfter=No
14	,	,	PUNCT	,	_	8	punct	8:punct	_
15	faster	faster	ADJ	JJR	Degree=Cmp	16	amod	16:amod	_
16	lens	lens	NOUN	NN	Number=Sing	4	list	4:list	_
17	at	at	ADP	IN	_	18	case	18:case	_
18	f/2	f/2	NOUN	NN	Number=Sing	16	nmod	16:nmod:at	_
19	and	and	CCONJ	CC	_	21	cc	21:cc|21.1:cc	_
20	the	the	DET	DT	Definite=Def|PronType=Art	21	det	21:det	_
21	SX40	SX40	PROPN	NNP	Number=Sing	16	conj	16:conj:and|21.1:nsubj	_
21.1	has	have	VERB	VBZ	_	_	_	16:conj:and	CopyOf=-1
22	only	only	ADJ	JJ	Degree=Pos	23	amod	23:amod	_
23	f	f	NOUN	NN	Number=Sing	21	orphan	21.1:obj	SpaceAfter=No
24	/	/	PUNCT	,	_	23	punct	23:punct	SpaceAfter=No
25	2.7	2.7	NUM	CD	NumType=Card	23	nummod	23:nummod	SpaceAfter=No
26	.	.	PUNCT	.	_	4	punct	4:punct	_```

[neetle]

I think this is relevant, but @ work so I can't verify it's the case. If it is, I'll see if I can extend lingo to deal with gapping entries.

[durp]

Since these are "empty nodes", isn't the expedient thing to simply skip word lines with an unspecified (_) head?

[neetle]

possibly - I believe (from what I can remember) that they're actually implied in the sentence. Not sure if giving up that fidelity is worth it.

[chewxy]

I am so sorry for not responding. apparently this library escaped my notifications. So I wasn't notified of incoming PRs and issues.