[pandas] SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame
转载自https://blog.csdn.net/blackyuanc/article/details/77892784
问题场景：
在读取CSV文件后，在新增一个特征列并根据已有特征修改新增列的值，结果在修改的过程中碰到SettingWithCopyWarning警告。
报错的做法：
1 import pandas as pd 2 import numpy as np 3 4 aa = np.array([1,0,1,0]) 5 bb = pd.DataFrame(aa.T, columns=['one']) 6 7 bb['two'] = 0 8 9 for i in range(bb.shape[0]): 10 bb['two'][i] = 1 11 12 print(bb)
正确的做法：
1 # -*- coding: utf-8 -*- 2 import pandas as pd 3 import numpy as np 4 5 aa = np.array([1,0,1,0]) 6 bb = pd.DataFrame(aa.T, columns=['one']) 7 8 # 建立 9 two = np.zeros(bb.shape[0]) 10 11 # 修改 12 for i in range(bb.shape[0]): 13 two[i] = random.random() 14 15 # 插入 16 bb.insert(0,'two',two) 17 18 print(bb)
