--invert_hash doesn't work with --dsjson

[marco-rossi29]

This issue is present in both version 8.4.0 (commit 78e4ae7) and 8.6.1 (commit 94a6298).

Issue: Using DSJSON file here as data.txt and running:
vw.exe --dsjson data.txt --readable_model model.readable --invert_hash model.readable_inv --cb_adf
gives only 1 feature and the constant in model.readable_inv:

Version 8.6.1
Id 
Min label:-1.22449
Max label:0
bits:18
lda:0
0 ngram:
0 skip:
options: --hash_seed 0 --cb_adf --cb_type ips --csoaa_ldf multiline --csoaa_rank --link identity
Checksum: 62936095
event_sum 0
action_sum 0
:0
:26051:-0.0168612
Constant:116060:-0.0168612

whereas model.readable has ~190 features:

Version 8.6.1
Id 
Min label:-1.22449
Max label:0
bits:18
lda:0
0 ngram:
0 skip:
options: --hash_seed 0 --cb_adf --cb_type ips --csoaa_ldf multiline --csoaa_rank --link identity
Checksum: 62936095
event_sum 0
action_sum 0
:0
175:0.0513654
1982:-1.08739
2089:0.0265077
3437:0.00171433
3620:0.0620581
3923:-11.723
4765:0.00162573
5289:0.00970562
7524:-0.0468675
12196:0.00228014
12373:0.0449017
12553:0.63988
13266:-0.0716713
14327:0.00162573
16001:0.00162573
16565:0.0254798
19539:0.0105616
20477:0.0294717
21080:0.022225
22454:594.956
22788:0.00554071
23093:17.1233
23283:855.118
24121:-8.95805
24174:0.597908
24823:0.0270979
26051:-0.0168612
26553:-0.0536117
27399:0.0137574
27910:0.0100833
35901:0.0257047
36441:0.0254798
36831:0.0016337
38323:0.00162573
40990:0.0251746
41407:0.0213216
42868:0.0581745
43143:0.0100802
45848:0.0167105
47813:0.0212803
48026:0.108382
49356:0.00162573
53057:0.0101623
55125:0.0017898
55156:0.0214329
55384:6.36968
59949:0.0544446
61595:0.0254798
61666:0.00974771
63915:0.0016419
64110:0.00959619
66549:-0.0190973
72377:0.00162573
74138:0.00162573
75106:0.0254999
75981:0.00180222
77105:-5.79003
78004:0.0214775
78815:-0.0451893
79695:0.00162573
79900:0.00162573
80802:0.0016269
83044:0.00162573
83205:0.0540289
83321:0.0164848
84231:0.0113576
86597:0.0395648
86739:0.00162573
89785:-0.0527661
93058:0.00162573
94653:8.66265
95054:0.00920749
96482:0.0281576
98563:0.013353
99815:0.0099329
101042:0.0256731
103135:0.0547361
104000:68.4282
104155:0.00165006
105990:2.36476
106680:0.0544446
110002:-0.0190973
110338:27.7843
112177:0.013353
112729:0.030168
113804:0.013353
115073:0.0257047
115344:3.54633
116060:-0.0168612
119392:0.00230874
119652:0.0212803
119717:0.0327092
123962:0.00162573
124098:0.0267705
125209:3.05408
126417:0.00789929
128361:0.0392587
130819:0.00164846
131812:0.00162573
134629:0.010112
136730:0.00268611
139337:2.59888
140026:0.175844
141252:3.19846
144732:0.00162573
145330:0.0492531
145888:0.00252063
149238:0.0186415
150232:-1.73182
151096:0.200728
152187:0.0979684
152289:0.116092
152810:-0.134205
152984:0.00164002
155643:0.0100106
157471:3.80609
160537:4.45124
163964:0.0016269
166742:27.8495
172767:-0.0468675
175990:2.16485
176598:-0.0336927
176813:0.384276
178610:-0.0468675
179126:-0.328854
179966:0.0258893
180391:0.00162573
181868:0.0486424
183350:0.0212803
184440:0.00162573
185815:0.0016269
185868:0.0224254
186906:-0.0168612
187185:0.0186326
187295:0.114245
188970:-8.48921
190538:0.00162573
190809:0.399807
191905:0.0198237
194265:-6.00704
194843:0.00162573
195140:1.01341
195681:0.013353
197213:28.3185
198738:0.00371133
199171:0.160765
200048:-23.8867
200737:0.0430822
204571:0.015883
206544:0.00729267
206768:0.0212803
206850:0.013353
209343:0.321475
210713:0.0285368
216855:0.0107094
217656:0.0254798
218742:0.0330709
219144:-0.0473967
219687:0.149107
221342:0.0642925
222195:0.030631
223236:0.0285168
227378:0.00606413
229175:0.00999028
230019:1.41894
235673:0.0100562
240558:0.0472738
241456:0.0218051
241995:0.00162573
244364:0.0016269
244396:0.0677292
245652:0.0644517
246135:0.0121952
246866:0.0254798
247145:0.3251
249709:0.580481
249778:-0.0168612
250620:7.09266
251413:0.768552
251509:0.013353
251635:-0.0190973
251874:-53.5849
252385:1.2489
252509:0.0258934
253098:7.09266
257210:0.104905
258018:0.010041
259943:0.0213216
261623:5.32071

[jackgerrits]

This bug affects both --dsjson and --json, --invert_hash implicitly relies on some audit functionality. When using standard VW format this works correctly but when using json parsing it is not using audit. While I work on a proper fix there is a workaround to explicitly add --audit to your command line.

---

Temporary Workaround

When using --json or --dsjson add --audit to the command line.

[ataymano]

Cannot reproduce on current master.