PyROOT中RDataFrame.AsNumpy()报错：np.object已废弃的解决咨询

在Jupyter Notebook中使用PyROOT读取ROOT文件的TTree为RDataFrame，尝试将数据框列转换为Numpy数组时触发错误，已知降级Numpy可解决，但需要无需降级的方案。

完整代码 #

import ROOT
import sys
import numpy as np
import matplotlib.pyplot as plt
ROOT.ROOT.EnableImplicitMT()
%jsroot on
### INPUT STYLE 
runNumber = input()
n=33

while(runNumber != "0"):
    print(runNumber)
    fileName = path + f'run_{runNumber}/RAW/SDataR_run_{runNumber}.root'
    df = ROOT.RDataFrame("Data_R;", fileName)
    a=df.AsNumpy(["Channel"])
    print("Channel array: ", a)
    print("")
    print("Enter another run number, or '0' to exit")
    runNumber = input()

数据框结构 #

报错信息 #

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In[48], line 1
----> 1 a=df.AsNumpy(["Channel"])

File /usr/local/Cellar/root/6.26.06_2/lib/root/ROOT/_pythonization/_rdataframe.py:87, in RDataFrameAsNumpy(df, columns, exclude, lazy)
     85     return result
     86 else:
---> 87     return result.GetValue()

File /usr/local/Cellar/root/6.26.06_2/lib/root/ROOT/_pythonization/_rdataframe.py:138, in AsNumpyResult.GetValue(self)
    136     self._py_arrays[column] = ndarray(tmp, self._result_ptrs[column])
    137 else:
---> 138     tmp = numpy.empty(len(cpp_reference), dtype=numpy.object)
    139     for i, x in enumerate(cpp_reference):
    140         tmp[i] = x # This creates only the wrapping of the objects and does not copy.

File /Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/numpy/__init__.py:305, in __getattr__(attr)
    300     warnings.warn(
    301         f"In the future `np.{attr}` will be defined as the "
    302         "corresponding NumPy scalar.", FutureWarning, stacklevel=2)
    304 if attr in __former_attrs__:
---> 305     raise AttributeError(__former_attrs__[attr])
    307 # Importing Tester requires importing all of UnitTest which is not a
    308 # cheap import Since it is mainly used in test suits, we lazy import it
    309 # here to save on the order of 10 ms of import time for most users
    310 #
    311 # The previous way Tester was imported also had a side effect of adding
    312 # the full `numpy.testing` namespace
    313 if attr == 'testing':

AttributeError: module 'numpy' has no attribute 'object'.
`np.object` was a deprecated alias for the builtin `object`. To avoid this error in existing code, use `object` by itself. Doing this will not modify any behavior and is safe. 
The aliases was originally deprecated in NumPy 1.20; for more details and guidance see the original release note at:
    https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations

无需降级Numpy的解决方案 #

1. 升级ROOT到兼容版本 #

你的ROOT版本是6.26.06，该版本的PyROOT代码仍在使用已被Numpy弃用的np.object。ROOT 6.28及以上版本已经修复了这个兼容性问题，升级ROOT后即可直接使用AsNumpy方法。

2. 手动修补PyROOT的pythonization文件 #

找到报错的_rdataframe.py文件（路径：/usr/local/Cellar/root/6.26.06_2/lib/root/ROOT/_pythonization/_rdataframe.py），打开后定位到第138行，将numpy.object替换为原生的object，保存文件后重启Jupyter Notebook即可。

3. 绕过AsNumpy，手动提取数据 #

使用RDataFrame的Take方法直接提取数据，再转换为Numpy数组，示例代码如下：

# 替换原代码中的a=df.AsNumpy(["Channel"])
# 注意：根据Channel分支的实际类型修改<>中的类型，比如int/float等
channel_list = df.Take["int"]("Channel")
a = np.array(channel_list)

内容的提问来源于stack exchange，提问作者LuciaB