一个DataFrame赋值的诡异报错 A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc

DataFrame赋值时报错

A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copyself.obj[key] = _infer_fill_value(value)
D:\ProgramData\Anaconda3\envs\my3.6\lib\site-packages\pandas\core\indexing.py:1743: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copyisetter(ilocs[0], value)

在以前的版本上我们对dataFrame重新创建一列，并赋值可以直接：

arriveData.loc["dayInMonth"]=arriveData["Plan_date"].apply(getDayInMonth)

但是不知道从哪个版本开始就不行了，就会出现上面的报错。所以我们按照提示老实的改为：

arriveData.loc[:，"dayInMonth"]=arriveData["Plan_date"].apply(getDayInMonth)

然而错误还是那个错误，我记得曾就有个阶段这种赋值还是可以的，只能说版本更新太快，或者是python的报错信息出现了bug吧，通过查文档可以发现，赋值方法早已经发生了改变：

所以我就改成了这样：

arriveData.loc[:]["dayInMonth"]=arriveData["Plan_date"].apply(getDayInMonth)

然而还是不行，~~马上抑郁。。。吐血。从怀疑自己，到怀疑自己，到怀疑python。。。。经典的不知所措，最终灵感一现发现了问题。

原来我操作的数据来源于一个视图，我总是想在这个视图上进行数据的更改是不科学的，这样不利于数据维护。！哦，yes

改成上面这样之后，报错成功解决。

一个DataFrame赋值的诡异报错 A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc相关推荐

pandas 报警告：A value is trying to be set on a copy of a slice from a DataFrame
pandas 报警告:A value is trying to be set on a copy of a slice from a DataFrame 我在抽取了原来DataFrame数据的几列后, ...
Pandas - A value is trying to be set on a copy of a slice from a DataFrame
(想要直接解决问题的请直接拉到最后) 使用的DataFrame的 year state pop debt one 2000 Ohio 1.5 NaN two 1000 Ohio 1.7 1000 ...
SettingWithCopyWarning：A value is trying to be set on a copy of a slice from a DataFrame（Pandas库）
pandas警告SettingWithCopyWarning: A value is trying to ...原理和解决方案_Lucky0928的博客-CSDN博客以下内容是对这篇文章 ...
SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame
解决:SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame 在使用pand ...
SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame
SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame 设置拷贝警告:试图在 ...
成功解决A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,co
成功解决A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,co ...
成功解决SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame See
解决问题 SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame See ...
dataframe 添加列表到一个单元格并解决报错ValueError: Must have equal len keys and value when setting with an...
报错解析 import pandas as pd import numpy as npdf = pd.DataFrame(np.random.randint(0,10,size=(5, 2)),col ...
android addview指定位置,Android开发中，请问当在一个视图中addView另一个布局视图时为什么报错？...
Android开发中,我在一个视图中addView另一个布局视图(该视图通过inflate加载获得,其中root为null即没有附加parent视图),为什么还是会报错误: The specified ...

一个DataFrame赋值的诡异报错 A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc

DataFrame赋值时报错

一个DataFrame赋值的诡异报错 A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc相关推荐

最新文章

热门文章