OpenAI LLM: update `modelname_to_contextsize` with new models (#2843)

Token counts pulled from https://openai.com/pricing

langchain/llms/openai.py

@@ -476,13 +476,6 @@ class BaseOpenAI(BaseLLM):
     def modelname_to_contextsize(self, modelname: str) -> int:
         """Calculate the maximum number of tokens possible to generate for a model.
 
-        text-davinci-003: 4,097 tokens
-        text-curie-001: 2,048 tokens
-        text-babbage-001: 2,048 tokens
-        text-ada-001: 2,048 tokens
-        code-davinci-002: 8,000 tokens
-        code-cushman-001: 2,048 tokens
-
         Args:
             modelname: The modelname we want to know the context size for.
 
@@ -494,20 +487,37 @@ class BaseOpenAI(BaseLLM):
 
                 max_tokens = openai.modelname_to_contextsize("text-davinci-003")
         """
-        if modelname == "text-davinci-003":
-            return 4097
-        elif modelname == "text-curie-001":
-            return 2048
-        elif modelname == "text-babbage-001":
-            return 2048
-        elif modelname == "text-ada-001":
-            return 2048
-        elif modelname == "code-davinci-002":
-            return 8000
-        elif modelname == "code-cushman-001":
-            return 2048
-        else:
-            return 4097
+        model_token_mapping = {
+            "gpt-4": 8192,
+            "gpt-4-0314": 8192,
+            "gpt-4-32k": 32768,
+            "gpt-4-32k-0314": 32768,
+            "gpt-3.5-turbo": 4096,
+            "gpt-3.5-turbo-0301": 4096,
+            "text-ada-001": 2049,
+            "ada": 2049,
+            "text-babbage-001": 2040,
+            "babbage": 2049,
+            "text-curie-001": 2049,
+            "curie": 2049,
+            "davinci": 2049,
+            "text-davinci-003": 4097,
+            "text-davinci-002": 4097,
+            "code-davinci-002": 8001,
+            "code-davinci-001": 8001,
+            "code-cushman-002": 2048,
+            "code-cushman-001": 2048,
+        }
+
+        context_size = model_token_mapping.get(modelname, None)
+
+        if context_size is None:
+            raise ValueError(
+                f"Unknown model: {modelname}. Please provide a valid OpenAI model name."
+                "Known models are: " + ", ".join(model_token_mapping.keys())
+            )
+
+        return context_size
 
     def max_tokens_for_prompt(self, prompt: str) -> int:
         """Calculate the maximum number of tokens possible to generate for a prompt.

tests/integration_tests/llms/test_openai.py

@@ -211,3 +211,14 @@ async def test_openai_chat_async_streaming_callback() -> None:
     result = await llm.agenerate(["Write me a sentence with 100 words."])
     assert callback_handler.llm_streams != 0
     assert isinstance(result, LLMResult)
+
+
+def test_openai_modelname_to_contextsize_valid() -> None:
+    """Test model name to context size on a valid model."""
+    assert OpenAI().modelname_to_contextsize("davinci") == 2049
+
+
+def test_openai_modelname_to_contextsize_invalid() -> None:
+    """Test model name to context size on an invalid model."""
+    with pytest.raises(ValueError):
+        OpenAI().modelname_to_contextsize("foobar")