Fix doc for PerceptionLMForConditionalGeneration forward. (#40733)

* Fix doc for PerceptionLMForConditionalGeneration forward.

* fix last nit

---------

Co-authored-by: raushan <[email protected]>

Author: shuminghu

src/transformers/models/perception_lm/modeling_perception_lm.py

@@ -374,23 +374,44 @@ def forward(
         Example:
 
         ```python
-        >>> from PIL import Image
-        >>> import requests
-        >>> from transformers import AutoProcessor, PerceptionLMForConditionalGeneration
-
-        >>> model = PerceptionLMForConditionalGeneration.from_pretrained("perception_lm-hf/perception_lm-1.5-7b-hf")
-        >>> processor = AutoProcessor.from_pretrained("perception_lm-hf/perception_lm-1.5-7b-hf")
-
-        >>> prompt = "USER: <image>\nWhat's the content of the image? ASSISTANT:"
-        >>> url = "https://www.ilankelman.org/stopsigns/australia.jpg"
-        >>> image = Image.open(requests.get(url, stream=True).raw)
-
-        >>> inputs = processor(images=image, text=prompt, return_tensors="pt")
+        from transformers import AutoProcessor, AutoModelForImageTextToText
+        from huggingface_hub import hf_hub_download
+
+        MODEL_PATH = "facebook/Perception-LM-1B"
+        processor = AutoProcessor.from_pretrained(MODEL_PATH, use_fast=True)
+        model = AutoModelForImageTextToText.from_pretrained(MODEL_PATH).to("cuda")
+        test_image_file = hf_hub_download(
+                    repo_id="shumingh/perception_lm_test_images",
+                    filename="14496_0.PNG",
+                    repo_type="dataset",
+        )
+        conversation = [
+            {
+                "role": "user",
+                "content": [
+                    {
+                        "type": "image",
+                        "url": test_image_file,
+                    },
+                    {"type": "text", "text": "Describe the bar plot in the image."},
+                ],
+            }
+        ]
+
+        inputs = processor.apply_chat_template(
+            [conversation],
+            add_generation_prompt=True,
+            tokenize=True,
+            return_dict=True,
+            return_tensors="pt",
+        )
+        inputs = inputs.to(model.device)
+        generate_ids = model.generate(**inputs, max_new_tokens=256)
+        input_length = inputs["input_ids"].shape[1]
+        generate_ids_without_inputs = generate_ids[:, input_length:]
 
-        >>> # Generate
-        >>> generate_ids = model.generate(**inputs, max_new_tokens=15)
-        >>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
-        "USER:  \nWhat's the content of the image? ASSISTANT: The image features a busy city street with a stop sign prominently displayed"
+        for output in processor.batch_decode(generate_ids_without_inputs, skip_special_tokens=True):
+            print(output)
         ```"""
         outputs = self.model(
             input_ids=input_ids,

src/transformers/models/perception_lm/modular_perception_lm.py

@@ -335,6 +335,54 @@ def forward(
         logits_to_keep: Union[int, torch.Tensor] = 0,
         **lm_kwargs,
     ) -> Union[tuple, PerceptionLMCausalLMOutputWithPast]:
+        r"""
+        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
+            Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
+            config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
+            (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.
+
+        Example:
+
+        ```python
+        from transformers import AutoProcessor, AutoModelForImageTextToText
+        from huggingface_hub import hf_hub_download
+
+        MODEL_PATH = "facebook/Perception-LM-1B"
+        processor = AutoProcessor.from_pretrained(MODEL_PATH, use_fast=True)
+        model = AutoModelForImageTextToText.from_pretrained(MODEL_PATH).to("cuda")
+        test_image_file = hf_hub_download(
+                    repo_id="shumingh/perception_lm_test_images",
+                    filename="14496_0.PNG",
+                    repo_type="dataset",
+        )
+        conversation = [
+            {
+                "role": "user",
+                "content": [
+                    {
+                        "type": "image",
+                        "url": test_image_file,
+                    },
+                    {"type": "text", "text": "Describe the bar plot in the image."},
+                ],
+            }
+        ]
+
+        inputs = processor.apply_chat_template(
+            [conversation],
+            add_generation_prompt=True,
+            tokenize=True,
+            return_dict=True,
+            return_tensors="pt",
+        )
+        inputs = inputs.to(model.device)
+        generate_ids = model.generate(**inputs, max_new_tokens=256)
+        input_length = inputs["input_ids"].shape[1]
+        generate_ids_without_inputs = generate_ids[:, input_length:]
+
+        for output in processor.batch_decode(generate_ids_without_inputs, skip_special_tokens=True):
+            print(output)
+        ```"""
         outputs = self.model(
             input_ids=input_ids,
             pixel_values=pixel_values,