如何使用pyarrow将Pandas数据帧设置/获取到Redis中

Question

使用

dd = {'ID': ['H576','H577','H578','H600', 'H700'],
      'CD': ['AAAAAAA', 'BBBBB', 'CCCCCC','DDDDDD', 'EEEEEEE']}
df = pd.DataFrame(dd)

在Pandas 0.25之前，这在下面起作用。

set:  redisConn.set("key", df.to_msgpack(compress='zlib'))
get:  pd.read_msgpack(redisConn.get("key"))

现在，已弃用警告。

FutureWarning: to_msgpack is deprecated and will be removed in a future version.
It is recommended to use pyarrow for on-the-wire transmission of pandas objects.

The read_msgpack is deprecated and will be removed in a future version.
It is recommended to use pyarrow for on-the-wire transmission of pandas objects.

骨髓如何运作？而且，我如何使pyarrow对象进出Redis。

参考：
如何在Redis中设置pandas.DataFrame或从Redis获取pandas.DataFrame？

Answer 1

这是一个使用pyarrow序列化熊猫数据帧以存储在Redis中的完整示例

apt-get install python3 python3-pip redis-server
pip3 install pandas pyarrow redis

然后在python中

import pandas as pd
import pyarrow as pa
import redis

df=pd.DataFrame({'A':[1,2,3]})
r = redis.Redis(host='localhost', port=6379, db=0)

context = pa.default_serialization_context()
r.set("key", context.serialize(df).to_buffer().to_pybytes())
context.deserialize(r.get("key"))
   A
0  1
1  2
2  3

我刚刚向熊猫提交了PR 28494，以便在文档中包含这个pyarrow示例。

参考文档：

• https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.to_msgpack.html
• https://arrow.apache.org/docs/python/ipc.html#arbitrary-object-serialization
• https://arrow.apache.org/docs/python/memory.html#pyarrow-buffer
• https://stackoverflow.com/a/37957490/4126114