Better Error Description

[crystina-z]

Currently some error messages are not quite helpful to identify the problem, say:

1. when the runfile is somehow broken (e.g. if anserini was interrupted during the searching and left the runfile halfly written)

   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/evaluator.py", line 131, in search_best_run
   runs = Searcher.load_trec_run(runfile)
   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/searcher/__init__.py", line 38, in load_trec_run
   qid, _, docid, rank, score, desc = line.split(" ")
   ValueError: not enough values to unpack (expected 6, got 1)

2. when runfile does not contain any qid in test set:

   ~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/evaluator.py:56: RuntimeWarning: Mean of empty slice.
   scores = np.array(scores).mean(axis=0).tolist()
   ~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/numpy/core/_methods.py:170: RuntimeWarning: invalid value encountered in double_scalars
   ret = ret.dtype.type(ret / rcount)
   Traceback (most recent call last):
   ...
   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/task/rerank.py", line 42, in train
   rank_results = self.rank.evaluate()
   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/task/rank.py", line 55, in evaluate
   self.get_results_path(), self.benchmark, primary_metric=self.config["optimize"], metrics=metrics
   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/evaluator.py", line 138, in search_best_run
   benchmark.relevance_level,
   File "~/anaconda3/envs/MyCapreolus/lib/python3.7/site-packages/capreolus/evaluator.py", line 57, in _eval_runs
   scores = dict(zip(metrics, scores))
   TypeError: zip argument #2 must support iteration

Todo: handle these errors in a way that even first time users would know what's happening

[andrewyates]

This is also related to #99. Maybe what we need is some validation of the file format, so that we can raise our own exception?

[andrewyates]

Was this handled by #174?

[crystina-z]

u mean #178? Yup I think so