Fix unintuitive `--gen_kwargs` behavior (#1329)

* don't override do_sample if no value for it is passed

* Update gen_kwargs override condition

* Update huggingface.py

* Update huggingface.py

* run linters

* silence an erroneous warning

lm_eval/evaluator.py

@@ -140,9 +140,12 @@ def simple_evaluate(
                 )
             else:
                 default_num_fewshot = config["num_fewshot"]
-                eval_logger.warning(
-                    f"Overwriting default num_fewshot of {task_name} from {default_num_fewshot} to {num_fewshot}"
-                )
+                if default_num_fewshot:
+                    # warn a user, if a specific num_fewshot > 0 was specified.
+                    # if unspecified in config, no warning message
+                    eval_logger.warning(
+                        f"Overwriting default num_fewshot of {task_name} from {default_num_fewshot} to {num_fewshot}"
+                    )
 
                 task_obj._config["num_fewshot"] = num_fewshot
 

lm_eval/models/huggingface.py

@@ -705,10 +705,12 @@ class HFLM(LM):
                 return self.model(inps).logits
 
     def _model_generate(self, context, max_length, stop, **generation_kwargs):
-        # we require users to pass do_sample=True explicitly
-        # for non-greedy gen. This should be reevaluated when considering beam search.
-        if "do_sample" not in generation_kwargs:
-            generation_kwargs["do_sample"] = False
+        # if do_sample is false and temp==0.0:
+        # remove temperature, as do_sample=False takes care of this
+        # and we don't want a warning from HF
+        do_sample = generation_kwargs.get("do_sample", None)
+        if do_sample is False and "temperature" == 0.0:
+            generation_kwargs.pop("temperature", 0.0)
         # build stopping criteria
         stopping_criteria = stop_sequences_criteria(
             self.tokenizer, stop, context.shape[1], context.shape[0]

lm_eval/tasks/gsm8k/gsm8k.yaml

@@ -24,6 +24,7 @@ generation_kwargs:
     - "\n\n"
     - "Question:"
   do_sample: false
+  temperature: 0.0
 repeats: 1
 num_fewshot: 5
 filter_list: