feat(google-common): Gemini logprobs

docs/core_docs/docs/integrations/chat/google_vertex_ai.ipynb

@@ -41,7 +41,9 @@
         "\n",
         "| [Tool calling](/docs/how_to/tool_calling) | [Structured output](/docs/how_to/structured_output/) | JSON mode | [Image input](/docs/how_to/multimodal_inputs/) | Audio input | Video input | [Token-level streaming](/docs/how_to/chat_streaming/) | [Token usage](/docs/how_to/chat_token_usage_tracking/) | [Logprobs](/docs/how_to/logprobs/) |\n",
         "| :---: | :---: | :---: | :---: |  :---: | :---: | :---: | :---: | :---: |\n",
-        "| ✅ | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ | \n",
+        "| ✅ | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | \n",
+        "\n",
+        "Note that while logprobs are supported, Gemini has fairly restricted usage of them.\n",
         "\n",
         "## Setup\n",
         "\n",

libs/langchain-google-common/src/chat_models.ts

@@ -189,8 +189,16 @@ export abstract class ChatGoogleBase<AuthOptions>
 
   topK = 40;
 
+  presencePenalty = undefined;
+
+  frequencyPenalty = undefined;
+
   stopSequences: string[] = [];
 
+  logprobs: false;
+
+  topLogprobs: 0;
+
   safetySettings: GoogleAISafetySetting[] = [];
 
   // May intentionally be undefined, meaning to compute this.

libs/langchain-google-common/src/tests/chat_models.test.ts

@@ -1250,6 +1250,39 @@ describe("Mock ChatGoogle - Gemini", () => {
 
     expect(record.opts.data.tools[0]).toHaveProperty("googleSearch");
   });
+
+  test("7. logprobs", async () => {
+    const record: Record<string, any> = {};
+    const projectId = mockId();
+    const authOptions: MockClientAuthInfo = {
+      record,
+      projectId,
+      resultFile: "chat-7-mock.json",
+    };
+
+    const model = new ChatGoogle({
+      authOptions,
+      modelName: "gemini-1.5-flash-002",
+      logprobs: true,
+      topLogprobs: 5,
+    });
+    const result = await model.invoke(
+      "What are some names for a company that makes fancy socks?"
+    );
+    // console.log(JSON.stringify(result,null,1));
+    expect(result.response_metadata).toHaveProperty("logprobs");
+    expect(result.response_metadata.logprobs).toHaveProperty("content");
+    const logprobs = result.response_metadata.logprobs.content;
+    expect(Array.isArray(logprobs)).toBeTruthy();
+    expect(logprobs).toHaveLength(303);
+    const first = logprobs[0];
+    expect(first.token).toEqual("Here");
+    expect(first.logprob).toEqual(-0.25194553);
+    expect(first.bytes).toEqual([72, 101, 114, 101]);
+    expect(first).toHaveProperty("top_logprobs");
+    expect(Array.isArray(first.top_logprobs)).toBeTruthy();
+    expect(first.top_logprobs).toHaveLength(5);
+  });
 });
 
 describe("Mock ChatGoogle - Anthropic", () => {