如何标记python中选定列中的离群值/anomaly？

Question

在下面的dataset df中。我想标记除A、B、C和L之外的所有列中的异常。

任何小于1,500或大于400000的值都被视为异常。

import pandas as pd
  
# intialise data of lists
data = { 
         'A':['T1', 'T2', 'T3', 'T4', 'T5'],
         'B':[1,1,1,1,1],
         'C':[1,2,3,5,9],
         'D':[12005, 18190, 1034, 15310, 31117],
        'E':[11021, 19112, 19021, 12, 24509 ],
        'F':[10022,19910, 19113,19999, 25519],
        'G':[14029, 29100, 39022, 24509, 412262],
        'H':[52119,32991,52883,69359,57835],
         'J':[41218, 52991,55121,69152,79355],
         'K': [43211,8199991,56881,212,77342],
          'L': [1,0,1,0,0],
          'M': [31211,42901,53818,62158,69325],
        
        }
  
# Create DataFrame
df = pd.DataFrame(data)
  
# Print the output.
df

尝试：

exclude_cols = ['A','B','C','L']

def flag_outliers(s, exclude_cols):
    if s.name in exclude_cols:
        return '' # or None, or whatever df.style() needs
    else:
        s = pd.to_numeric(s, errors='coerce')
        indexes = (s<1500)|(s>400000)
        return ['background-color: red' if v else '' for v in indexes]

df.style.apply(lambda s: flag_outliers(s, exclude_cols), axis=1)

代码的结果：

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所需的输出应如下所示：

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感谢您的努力！

Answer 1

如果您将子集设置为apply函数的参数，您将获得所需的内容。

exclude_cols = ['A','B','C','L']

def flag_outliers(s, exclude_cols):
    if s.name in exclude_cols:
        print(s.name)
        return '' # or None, or whatever df.style() needs
    else:
        s = pd.to_numeric(s, errors='coerce')
        indexes = (s<1500)|(s>400000)
        return ['background-color: yellow' if v else '' for v in indexes]

df.style.apply(lambda s: flag_outliers(s, exclude_cols), axis=1, subset=['D','E','F','G','H','J','K'])

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