Langchain 介绍与入门

pip install langchain

pip install langchain-cli

pip install --upgrade  langchain-google-genai

from langchain_google_genai import GoogleGenerativeAI

api_key = ""

llm = GoogleGenerativeAI(model="models/text-bison-001", google_api_key=api_key)
print(
    llm.invoke(
        "What are some of the pros and cons of Python as a programming language?"
    )
)

[root@dev T2Ranking]#python lang_chain_demo.py 
**Pros of Python:**

* **Simplicity:** Python is a relatively easy-to-learn language, with a simple syntax that is easy to read and write. This makes it a good choice for beginners and experienced programmers alike.
* **Versatility:** Python can be used for a wide variety of applications, including web development, data science, machine learning, and artificial intelligence. This makes it a good choice for developers who want to work on a variety of projects.
* **Libraries:** Python has a large and active community of developers who have created a wide variety of libraries and frameworks that can be used to extend the functionality of the language. This makes it easy to add new features and functionality to Python applications.
* **Cross-platform:** Python is cross-platform, which means that it can be run on a variety of operating systems, including Windows, macOS, and Linux. This makes it a good choice for developers who want to develop applications that can be used on multiple platforms.
* **Open source:** Python is an open-source language, which means that it is free to use and modify. This makes it a good choice for developers who want to create custom applications or who want to contribute to the development of the language itself.

**Cons of Python:**

* **Speed:** Python is not as fast as some other programming languages, such as C or C++. This can be a disadvantage for applications that require high performance.
* **Memory usage:** Python can also be more memory-intensive than other programming languages. This can be a disadvantage for applications that need to run on devices with limited memory.
* **Lack of static typing:** Python is a dynamically typed language, which means that the type of a variable is not known until runtime. This can make it difficult to catch errors early on in the development process.
* **Lack of support for multithreading:** Python does not have built-in support for multithreading. This can make it difficult to develop applications that can take advantage of multiple processors.
* **Security:** Python is not as secure as some other programming languages. This can be a disadvantage for applications that need to handle sensitive data.

import sys  
from langchain_google_genai import GoogleGenerativeAI

api_key = ""
llm = GoogleGenerativeAI(model="gemini-pro", google_api_key=api_key)

  
for chunk in llm.stream("Tell me a short poem about snow"):  
	sys.stdout.write(chunk)  
	sys.stdout.flush()

from langchain_google_genai import GoogleGenerativeAI
from langchain.prompts import PromptTemplate

api_key = ""

llm = GoogleGenerativeAI(model="gemini-pro", google_api_key=api_key)
# print(
#     llm.invoke(
#         "What are some of the pros and cons of Python as a programming language?"
#     )
# )

template = """Question: {question}  
  
Answer: Let's think step by step."""  
prompt = PromptTemplate.from_template(template)  
  
chain = prompt | llm  
  
question = "How much is 2+2?"  
print(chain.invoke({"question": question}))

[root@dev T2Ranking]#python lang_chain_demo.py 
2+2 is a basic arithmetic problem. The answer is 4.